Cable pulling system and components therefor

ABSTRACT

Cable pulling systems and methods of use are provided suitable for trenchless cable pulling applications, including bursting head applications for laying down replacement pipe underground. A chassis is provided that accommodates laterally disposed piston assemblies, both single cylinder and dual cylinder closed path piston assemblies. Also provided are quick release manifolds for cable holding grippers and cable pulling grippers for use with both single cylinder and dual cylinder piston assemblies. A chassis and cable pulling system also are provided for trenchless pipe extraction applications and which accommodate closed path piston assemblies. Small and large pipe diameter bursting head devices also are provided with integrated cable gripping and release assemblies. Also provided are methods for sealing cable ends.

FIELD OF USE

Embodiments of the present disclosure find applicability in the field ofsystems designed to pull cable and/or pipe, particularly for pullingcable and/or pipe through space underground. One useful field includessystems for bursting and placing gas, water, sewer or other undergroundpipes.

BACKGROUND

Trenchless cable pulling systems and trenchless pipe bursting/pipereplacement systems are a fast growing standard in the pipe replacementindustry. Such “trenchless” systems require only two pits to be dug, oneat each end of the pipe to be replaced. One end of a pulling cable isattached to the front end of a bursting pipe head device, and the otherend is threaded through the existing pipe from an entry point accessiblein the entry pit and provided to a pulling apparatus located in the exitpit. The pulling apparatus then pulls the cable and the attachedbursting pipe head device through the existing cable, typically by ahydraulic mechanism which may be electrical or gas-powered. The burstingpipe head device bursts or fractures the existing pipe as it is pulledthrough, and brings with it replacement or product pipe attached at theback end of the bursting pipe head device. Pat. Nos. US PatentApplication Publications US 2002/0081154; US 2006/0088384; US2008/0181728; US 2104/0241812; and U.S. Pat. Nos. 6,305,880; 6,357,967;6,672,802; 6,913,091; 6,799,923; 7,284,624; 8,414,225; 8,540,458;8,702,349; 8,784,009; and 8,979,435 are representative of the state ofthe art.

There is an on-going desire to improve these trenchless pulling systems,including to: (1) minimize the size of the pits to be dug; (2) reducethe weight and size of the pulling apparatus; (3) provide maximumflexibility for hydraulic power sources; (4) enhance cable fidelity andminimize breakage or binding during the cable pulling process; (5)increase the facility and ease for engaging cable with and disengagingcable from both the pulling apparatus and the bursting head; (6)increase the facility and ease for cable disengagement for large andsmall pipe diameter bursting heads; (7) increase the facility and easeof maintaining and using small and large pipe diameter bursting pipehead devices; and (8) managing pipe extraction in small diameter pipereplacement applications.

The present disclosure describes improvements in cable pulling systemsand methods and trenchless replacement pipe pulling systems and methodsthat overcome deficiencies in the systems and methods of the prior art.

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key features ofthe claimed subject matter on its own, nor is it intended to be used onits own as an aid in determining the scope of the claimed subject matteror to limit the scope of the claimed subject matter. Similarly, theadvancements to the art provided by the disclosure made herein are notlimited to implementations that address the particular techniques,tools, environments, disadvantages, or advantages discussed in theBackground, Detailed Description or attached drawings.

Provided herein are cable pulling systems, apparatuses, and componentsmethods of use therefor suitable for trenchless cable pullingapplications, including bursting head applications for laying downreplacement pipe underground. In one embodiment, a chassis and systemare provided that accommodate laterally disposed piston assemblies,including single cylinder or dual cylinder closed path pistonassemblies. In another embodiment, improvements in single and dualcylinder piston assemblies suitable for cable pulling systems areprovided. These improvements include single cylinder piston assemblieswith internal debris containment systems and with internal anti-rotationassemblies. In another embodiment, improvements in dual cylinder pistonassemblies are provided, including for laterally disposed assemblies andclosed path assemblies, including closed pathway high pressure dualcylinder ram systems. Also provided are quick release manifolds forcable holding grippers and for cable pulling grippers for use with bothsingle cylinder and dual cylinder piston assemblies. A chassis and cablepulling system also are provided for trenchless pipe extractionapplications and which accommodate closed path piston assemblies. Smalland large pipe diameter bursting head devices also are provided withintegrated cable gripping and release assemblies. In one embodimentthese integrated assemblies do not require tools to initiate cablegripping or release. Also provided are methods for sealing cable ends.

In one aspect, a detachable pipe splitting tool for cutting coaxial pipeextruded together with a cable being pulled through space and method ofuse therefor are provided. The tool comprises (a) means for receiving acable being pulled through space; (b) means for guiding a coaxiallylocated pipe surrounding the cable to at least one cutting blade distalto the cable receiving means, such that as the cable is pulled throughthe cable receiving means the pipe is split by the cutting blade; and(c) means for removably attaching the pipe splitting tool to a rigidsurface such that the tool extends perpendicularly from that surface. Inanother embodiment, the pipe splitting tool attaches to the rigidsurface by magnetic means.

In another aspect, a method for sealing a cable end is providedcomprising the steps of: (1) girdling a cable perimeter near the end tobe sealed so as to remove a portion of the cable outer perimeter andexpose a central stem; (2) providing a metal cuff having an interiordiameter dimensioned to receive the exposed stem and an outer diametersubstantially equal to the cable outer perimeter; (3) placing the cuffover the stem; and (4) providing a bonding material in liquid form tothe interface of the cable outer perimeter and the cuff, the bondingmaterial having a liquid and a solid form, such that the bondingmaterial infiltrates the interface and the cuff interior and bonds thestem and cable interface to the cuff when the bonding materialsolidifies. In one embodiment, the bonding material can be a solderingmaterial.

In another aspect, an integrated cable clamping and release mechanismuseful in a bursting head device is provided, the mechanism comprising(a) a gripper component comprising a plurality of gripper members, eachmember having an inner cable gripping surface, an outer tapered surfacedimensioned to interact with a tapered interior surface of a burstinghead cone, and opposing member adjoining surfaces having an indexedmagnet embedded therein and competent to repel a magnet on an adjoiningsurface; (b) a rigid component removably coupled to the distal end ofthe gripper component and having an axial cavity dimensioned to receivea cable; and (c) means for actuating longitudinal movement of theintegrated cable clamping and release mechanism in the bursting head,the actuating means being attached to the distal end of the rigidcomponent and having an operational end on the distal exterior surfaceof the bursting head, such that the actuating means can cause thegripper component to grip a cable surface by initiating forward movementof the integrated mechanism in the bursting head cone. The actuatingmeans also can cause the gripper component to release the cable byinitiating rearward movement of the integrated mechanism in the burstinghead cone. In one embodiment the structural component coupling comprisesan interlocking lip and groove mechanism. In another embodiment, thelongitudinal movement of the integrated mechanism initiated by theintegrated actuating means occurs by rotational movement of the rigidcomponent along a threaded channel in the bursting head device andengaged with the outer surface of the rigid component. In still anothercomponent, the threaded channel occurs in a bursting head device endcap.In another embodiment, the integrated actuating means operational endcan comprise a handle or a hex screw.

In another aspect, a pipe extraction apparatus comprising a chassis, apiston assembly competent to pull cable through space, a pulley, and apipe splitting tool is provided. The chassis comprises a faceplate and aback plate, each defining an aperture for receiving a cable andconnected by a plurality of side trusses; an angled shelf assemblyextending distally from the backplate and positioned above the backplateaperture, the shelf assembly being configured to receive and hold thepiston assembly. In one embodiment, the piston assembly can be a singleor dual cylinder closed path assembly. In another embodiment, the pipeextraction apparatus shelf assembly includes means for slidablyinterconnecting with the piston assembly.

In another aspect, an integrated cable release manifold is provided fora cable pulling device comprising a spring-loaded cable grippingassembly having a cable gripper component with a tapered proximal endand a compression spring component at its distal end. The manifoldincludes: (a) a housing having an aperture positioned to receive theproximal end of a cable gripper comprising a plurality of grippermembers, each member having an inner cable gripping surface and an outertapered surface dimensioned to interact with a tapered interior surfacein the cable pulling device; (b) means for attaching the manifoldhousing to the cable pulling device, and (c) actuating means forinitiating longitudinal movement of the spring-loaded cable grippingassembly rearward in the cable pulling device. In particular, theactuating means can be attached to an outer surface of the manifold andcompetent to contact the cable gripper proximal end, the contactinitiating rearward movement of the gripper away from the taperedinterior surface, compression of the distally located spring, andrelease of the gripper members from the cable surface. In one embodimentthe gripper members further comprise opposing member adjoining surfaceshaving an indexed magnet embedded therein and competent to repel amagnet on an adjoining surface. In another embodiment the actuatingmeans can comprise a multi-lead threaded piston that can contact theproximal gripper end by rotational movement of the piston along athreaded channel in the aperture. In another embodiment, rotation of thethreaded piston can be initiated by a lever attached to an outer surfaceof the threaded piston. In another embodiment, release of the actuatingmeans contact from the gripper component proximal end can initiatedecompression of the spring and forward longitudinal movement of thegripper members into the tapered interior and onto the cable surface.

In another aspect, a mechanism for modulating the rearward movement of acable gripper along a channel in a tapered cavity is provided. Here, thecable gripper comprises a plurality of gripper sections having an innercable gripping surface and an outer surface comprising a ridge engagedwith the channel and allowing travel of the gripper section along thechannel. The mechanism can include engagement means for removablyengaging the cable gripper in the channel, the engagement meanscomprising a torsion spring activated by the gripper rearward movementwhen the engagement means is engaged with the gripper, and configured tomodulate the speed and distance of the gripper rearward movement in thechannel. The mechanism also can include a housing containing theengagement means and comprising means for attaching to the distal end ofthe tapered cavity. In one embodiment, the gripper can comprise a pinextending out from a surface of the gripper, and the engagement meanscan include a lever arm defining a catch that engages the pin and canextend rearward with the traveling gripper. In another embodiment, thecatch can define an angled channel on the lever arm along which the pintravels during its rearward movement. In another embodiment, the gripperchannel comprises a groove in a tapered cavity at the open distal end ofa piston rod, such that forward movement of the piston rod initiatesrearward movement of the gripper along the channel and off a cablesurface; rearward movement of the piston rod initiates forward movementof the gripper along the channel and onto the cable surface, and theengagement means is provided to the open distal cavity in the housing.In another embodiment the gripper comprises two gripper sections, eachhaving a pin, and the engagement means includes two lever arms attachedto the torsion spring and configured to catch the pins.

In another aspect a latching means is provided that holds the engagementin an extended position away from the gripper distal end so that thegrippers can be removed. In one embodiment, the latching means caninclude a hinged bar attached to the engagement means housing and havingan angled channel that can engage a pin on a lever arm and hold the armextended.

In another aspect, an internal anti-rotation mechanism useful for ansingle cylinder piston assembly is provided. In one embodiment themechanism includes: (a) a hollow piston rod having an axial opening forreceiving a cable, the interior surface of the piston rod beingdimensioned to receive a shaft and allow longitudinal movement of thepiston rod along a portion of the shaft's outer surface, and the pistonrod interior surface further comprising a slot along its longitudinalaxis; and (b) a hollow shaft dimensioned to fit in the hollow piston rodand having an axial opening for receiving a cable, and comprising aprotrusion extending perpendicularly from the shaft outer surface anddimensioned to fit in the slot, such that lateral rotation of the pistonrod relative to the shaft is inhibited as the piston rod travelslongitudinally along the shaft. In one embodiment the piston rodinterior surface comprises a plurality of channels and the shaft outersurface includes a matching number of protrusions.

In another aspect, an internal cable debris containment mechanism usefulin a single cylinder piston assembly is provided. The mechanism caninclude a telescoping hollow channel dimensioned to allow cable passagetherethrough to the interior of the piston rod, such that the distal endof the shaft is coupled to the distal end of the piston rod, and cabledebris in the shaft interior is prevented from entering the piston rodinterior.

In another aspect a closed pathway dual cylinder piston assembly forpulling cable through space is provided. The piston assembly can includea housing, two piston rods, a cable holding gripping assembly andmanifold, and a cable pulling gripping assembly and manifold. Inparticular, the piston assembly housing can include: (1) two laterallydisposed cylindrical cavities having axial openings at the distal end ofthe housing and dimensioned to receive two piston rods; and (2) acentral axial channel positioned between the cavities and dimensioned toreceive a cable. In addition, the cable holding gripper assembly can bepositioned at the proximal end of the housing cable channel andconfigured to grip a cable surface during a piston recovery stroke. Theholding cable gripper manifold can be positioned anterior to the holdinggripper and provide means for coupling the assembly to a frame and meansfor releasing the gripper from a cable surface. The cable pullinggripper manifold can be attached to the free axial distal ends of thepiston rods in the assembly and can comprise a cable pulling grippingassembly aligned with the assembly housing's central axial channel andconfigured to grip a cable surface during a piston pulling stroke, andrelease the cable during the recovery stroke.

DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisdisclosure will become more readily appreciated as the same becomebetter understood by reference to the following detailed description,when taken in conjunction with the accompanying drawings, wherelike-numbered parts reference like-membered components and wherein:

FIG. 1 is an exploded perspective view of a cable pulling system with asingle cylinder piston assembly;

FIG. 2 is an exploded perspective view of a cable pulling system with aclosed bath dual cylinder piston assembly;

FIGS. 3A and 3B are perspective views of an assembled chassis (FIG. 3A)and exploded chassis (3B);

FIGS. 4A and 4B are perspective views of an assembled (4A) and explodedexploded (4B) cable pulling system with a single cylinder pistonassembly;

FIG. 5 is a cross section view of a single cylinder piston assembly withattached front and rear gripping manifolds;

FIGS. 6A-6C are perspective views of an internal wiper system;

FIG. 7 is an exploded view of a closed path dual cylinder pistonassembly;

FIG. 8 is a cross section view of the same closed path dual cylinderpiston assembly;

FIGS. 9A and 9B are perspective views of an assembled (9A) and anexploded (9B) front holding gripper manifold;

FIG. 10 is a cross section of a front holding gripper manifold;

FIGS. 11A-11D are assembled (11A), exploded (11B), rear (11C) and crosssection (11D) views of a front holding gripper manifold for a singlecylinder piston assembly;

FIGS. 12A-12D are rear (12A), perspective (12B), exploded top (12C), andexploded bottom (12D) views of a front holding gripper manifold for adual cylinder piston assembly;

FIG. 13 is an exploded view of a rear release latching assembly;

FIGS. 14A and 14B are assembled (14A) and exploded (14B) views of a pipeextraction chassis and pulling apparatus;

FIG. 15 is a rear view of a pipe extraction pulling apparatus;

FIGS. 16A and 16B are exploded (16A) and assembled (16B) views of a pipesplitter tool;

FIG. 17 is a cross-section of an integrated clamping jaw for a largediameter bursting head;

FIG. 18 is a cross-section of an integrated clamping jaw for a smalldiameter bursting head;

FIG. 19 is an exploded view of a large diameter bursting head device;

FIG. 20 is an exploded view of one small diameter bursting head device;

FIG. 21 is an exploded view of another small diameter bursting headdevice;

FIG. 22 is a cross-section of a large diameter bursting head cone;

FIGS. 23A and 23B are assembled (23A) and exploded (23B) views of asealed cable end.

DETAILED DESCRIPTION

Embodiments of the present disclosure provide devices, components,mechanisms and methods of use directed to systems for pulling a cable orpipe through space. Of particular applicability are trenchless systemsfor pulling a cable or pipe through space underground, includingtrenchless systems for pulling cable or replacement pipe through anexisting underground pipe.

TERMS AND DEFINITIONS

As used herein, the terms “chassis” and “frame” can be usedinterchangably and refer to a rigid structure typically designed toprovide support. As used herein, the terms “channel” or “groove” or“keyed path” can be used interchangably and refer to a slot in a firstcomponent that accommodates a second component having a ridge that fitsin the slot to couple both components. If desired, the slot can alsoallow the second component to travel along the path created by the slotin the first component. The terms “axial opening” and “aperture” bothrefer to an opening. The terms “cylinder” and “barrel” both refer to atubular shape with a central channel.

Materials

A range of suitable materials useful in the manufacture of the systems,apparatuses and components disclosed herein are well known in the artand can be used, as will be appreciated by those having ordinary skillin the art. Material choice will depend on the functionality of the itemand the corresponding need for durability, strength and weight. Forexample, choosing an aluminum material, particularly a high strengthaluminum, for components benefiting from low weight, such as, forexample, lateral piston assembly frame 110 or piston housings 116 or202, can be used to advantage. One useful such material includes 70/75aluminum. For other components a steel, including a mild steel,stainless steel or heat-tempered steel, can provide the desiredcharacteristics.

The systems, components and methods of use are described hereinbelow inthe following order:

I. Overall Cable Pulling System II. Chassis for Lateral Piston AssemblyIII. Internal Anti-Rotation Single Cylinder Piston & Wiper Assembly IV.Closed Path Dual Cylinder Piston Assembly V. Holding Gripper AssemblyVI. Holding Gripper Quick Release Manifold VII. Rear Pulling Gripper andCable Release Latch Assembly VIII. Small Diameter Pipe ExtractionChassis IX. Rear Cable Release Pipe Bursting Head X. Sealed Cable EndsXI. Method of Operation

I. Overall Cable Pulling System

Referring to FIGS. 1 and 2, two embodiments of a cable pulling system inaccordance with the present disclosure is shown. The system 100 caninclude a cable pulling apparatus 102, which can pull a cable 104. Inthese illustrated embodiments, cable 104 is attached to a bursting head106 and replacement pipe attachment assembly 108. As pulling apparatus102 pulls bursting head 106 through space underground, such as throughan existing pipe underground (not shown). Bursting head 106 can burstthe existing pipe and replacement pipe (not shown) can be pulled intoplace inside the void left by bursting head 106.

The pulling apparatus 102 can include a frame 110 that supports alaterally positioned piston assembly 111. Frame 110 can include afaceplate 140. Unless otherwise noted, throughout this detaileddescription, faceplate 160 identifies the front or anterior orientationof system 100 and its components. Piston assembly 111 may be a single ormultiple cylinder assembly (see below). In FIG. 1 piston assembly 111includes a closed path single cylinder center hole ram assembly 114having an outer barrel housing 116, an internal piston rod 118 and ashaft 119. Piston rod 118 defines an axial hole or channel 120 extendingthrough piston rod 118 dimensioned to allow cable passage therethroughand to an internal front pulling gripper system 130 configured to gripcable 104 and pull it through the piston assembly. Piston assembly 114further can include an internal telescoping wiper system 135 for keepingdebris from impacting the piston mechanism. In FIG. 2 the pistonassembly is a closed path dual cylinder ram assembly 200 comprising ahousing 202 that encases two piston cylinders 204 flanking a centralchannel 206 for cable passage through housing 202, at least part of thechannel having an inner surface dimensioned to receive a front cablepulling gripper assembly 130 configured to grip cable 104 and pull itthrough the piston assembly. This pulling occurs in response torepeating pulling strokes of piston 114 or 204 in a pulling direction,each pulling stroke being followed by a recovery stroke of piston 118 or204 in a recovery direction that is opposite the pulling direction. Indual piston assembly 200, cylinders 204 operate in tandem.

Piston assembly 111 further includes rear pulling gripper assembly 138for pulling cable 104 during the piston pulling stroke and releasingcable 104 during the piston recovery stroke. In FIG. 1 rear pullinggripper assembly 138 includes a manifold 137 configured for a singlecylinder piston assembly 114. In FIG. 2, rear pulling gripper assembly138 includes a manifold 210 configured for a dual cylinder pistonassembly 200. Rear pulling gripper assembly 138 further can include aspring tension latch system 129 configured to release the rear pullinggrippers from assembly 138.

A piston assembly 111 further can include a front manifold assembly 160which provides means for moving holding gripper system 130 into positionfor gripping cable 104, or out of position so cable can be released frompulling apparatus 110. Holding gripper system 130 is configured to gripcable 104 and hold it during a piston recovery stroke, and to let cable104 slide during the pulling stroke.

Pulling apparatus 110 has the advantage of providing a frame adapted fordifferent laterally positioned piston assemblies, including single anddual cylinder assemblies. Laterally positioned piston assemblies havethe advantage of not requiring a pulley to redirect cable 104 beforecable 104 reaches the piston assembly and pulling gripper assembly. Notrequiring a pulley and a structure to hold a vertically positionedpiston assembly in place can reduce system cost and weight, and reducethe size of the exit pit to be dug. It also can increase cable life andintegrity for a given cable type.

The subject matter defined in the appended claims is not necessarilylimited to the benefits described herein. A particular implementation ofthe advancements to the art disclosed herein may provide all, some ornone of the benefits described herein. Although operations for thevarious techniques may be described herein in a particular sequentialorder for the sake of presentation, it will be understood that thismanner of description encompasses rearrangements in the order ofoperations, unless a particular ordering is required. For example,operations or acts described sequentially may in some cases berearranged or performed concurrently.

Components of the cable/pipe pulling system 100 will now be described.It should be understood that this description and the accompanyingillustrations depict several examples of a cable pulling system, pipebursting apparatus and methods of use, and changes may be made to thestructure and function of the system and apparatus without departingfrom the essence to the advancements to the art made by the disclosureherein. Also, some standard features of the system and componentstherefor (e.g., some screws for securing parts together, etc.) may notbe described in detail for the sake of brevity and clarity in thedescription. Those skilled in the art will understand their inclusion.

II. Chassis for Lateral Piston Assembly

Useful cable pulling and replacement pipe pulling systems typicallyutilize a hydraulic cylinder or piston mechanism, also known in the artas a ram puller, to pull a cable. Many cable pulling systems in the artutilize a dual cylinder piston assembly. Dual piston assemblies of theart typically have an open pathway, with the cable exposed between thetwo cylinders. Generally, although not always, the dual piston assemblyis configured in a vertical position, perpendicular to the ground andsupported by a frame extending up from the exit pit. The cable exitingthe existing pipe underground pipe horizontally into the exit pit ismaneuvered up between the open path cylinders, typically by means of apulley, and is held in place by a cable pulling gripping system. U.S.Pat. Nos. 6,305,880; 6,672,802; and 6,799,923 are representative of thisart. Where dual piston assemblies are configured in a lateral position,the cylinders are dimensioned and spaced to allow a bursting head to bepulled out of the ground and into the space between them. U.S. Pat. No.8,702,349 is representative of this art.

Dual cylinder piston assemblies useful for pulling cable generally usehigh pressure to drive the cylinders (on the order of 10,000 psi) andcan run on smaller-sized power sources as compared with a singlecylinder system which generally uses low pressure (on the order of about3,000 psi). Disadvantages of vertical systems in the art are that theytend to be large and heavy, making them particularly difficult to use insmall spaces such as basements, crawl spaces, man holes, and septictanks. They also can be difficult to angle appropriately and can requireadditional frame structure to hold the pistons in place. Verticalsystems also require cable to be angled vertically, typically by meansof a pulley. This can impact the cable's integrity, depending on theangle used, cable size and pulling requirements of the system. Inlaterally positioned open pathway dual cylinder systems of the art,access to the bursting head can be cumbersome, and larger exit pits thandesired may be required. Described below is a compact, lightweightchassis designed to accommodate a laterally positioned ram puller, be ita single or dual cylinder assembly, and wherein the ram puller can bestaged for pulling or for easily accessing an extracted bursting head.Many features of chassis 110 are described in U.S. Pat. No. 8,540,458.

Referring to FIGS. 3A and 3B, the frame or chassis 110 can include aface plate 140 which can define a hole 142 therein that is large enoughfor a bursting head 106 to fit through. A pair of side panels 144 canextend back from opposite sides of face plate 140. Side panels 144 eachdefine a slot 146 that opens towards the opposite side panel 144. Eachslot 146 can extend forward from the back of the side panel 144, endingjust short of the front of side panel 144. Side panel 144 further caninclude a track 147 extending along the length of the interior side ofside panel 144 and positioned along the bottom of side panel 144 at aheight such that the base of a piston assembly 111 can travels along thetop edge of track 147 when the lateral protrusions 306 of pistonassembly front manifold body 302 are engaged in slots 146. In theembodiment illustrated in FIG. 3A, piston assembly 111 is a dualcylinder piston assembly. In one embodiment track 147 is made of a hardplastic to facilitate travel along the track. Each side panel 144 canalso include a front pin hole 150 and a rear pin hole 152 that bothextend from a top of side panel 144 above slot 146 and down into sidepanel 144 below slot 146. Pins 153 can be placed through pin holes 150and 152. Additionally, truss 154 can extend between lower portions ofside panels 144 to secure side panels 144 together. Face place 140, sidepanels 144 and trusses 154 can be rigidly secured together so that frame110 is rigid. Side panels 144 also can include one or more openings 155to reduce overall frame weight and/or to provide handles. Choice ofmaterials also can reduce overall frame weight. In one embodiment,lateral piston assembly frames can advantageously be made of aluminumand have an overall weight of less than about 55 lbs. In anotherembodiment, the assembled frame can have an overall length of less thanabout 24 inches, an overall height of less than about 18 inches, and anoverall width of less than about 14 inches.

Frame 110 with slots 146 and pins 153 allow a laterally positionedpiston assembly 111 as described herein to be contained within thechassis during all stages of operation. This provides for a compactsystem that can fit into small spaces. In particular, as describedhereinbelow, during a cable pulling operation pins 153 can hold a pistonassembly in a distal position relative to chassis faceplate 140, andpiston cycling, for example to pull a bursting head and replacement pipethrough a n existing buried pipe, occurs within the chassis interior.Once the bursting head is at the pipe exit, the piston assembly can berestaged at a second forward position and secured there with pins 153placed in forward pin holes 150. The interior of chassis 110 now is freefor the bursting head to be pulled into its interior for removal fromthe replacement pipe.

Faceplate 140 can be positioned against material surrounding a tunnel orhole (e.g., against material surrounding an end of an existing pipe)from which cable 104 and a bursting head 106 can emerge. Faceplate 140can act as a brace and keep frame 110 from being pulled into the tunnelor hole. If faceplate 140 is insufficient for this purpose, anadditional backup or resistance plate may be placed between thefaceplate and the cable exit hole. In addition or alternatively, timbersor other materials may be used to brace the faceplate. In oneembodiment, the resistance plate can have an opening of sufficientdiameter for a cable to pass through, and an opening sufficient for abursting head to pass through. In another embodiment, these openings areseparate. In still another embodiment, the separate openings arevertically aligned and connected via a channel of sufficient width toallow passage of a cable therethrough, and vertical movement of theresistance plate aligns the desired resistance plate opening withfaceplate opening 142.

III. Internal Anti-Rotation Single Cylinder Piston & Wiper Assembly

Referring to FIG. 1 and FIGS. 4-6 a single cylinder piston assembly 114for lateral positioning in a chassis is described. The piston assemblydescribed herein provides improvements on the single cylinder assemblydisclosed in U.S. Pat. No. 8,540,458, referred to therein as a centerhole ram assembly. The center hole ram assembly embodiments disclosedherein include a single cylinder piston with an internal anti-rotationmechanism and internal wiper system.

Single cylinder piston assembly 114 includes barrel housing 116,internal piston rod 118, axial opening 120 providing a centralsubstantially hollow channel configured for cable passage through pistonassembly 114, and shaft 119 defining at least part of the internalchannel through piston assembly 114 for cable passage. The outer surfaceof piston rod 118 may include a visual indicator of when piston rod 118is nearing the end of its pulling stroke. The visual indicator mayadvantageously include a band of color positioned on the piston rod 118external surface such that the band is exposed to view as piston rodnears the end of its pulling stroke. Presence of a visual indicator maysupport an operator in proper and timely cycling of piston rod 118 inbarrel housing 116.

An internal anti-rotation mechanism can be provided that limits lateralrotation of piston rod 118 relative to housing 116 or shaft 119 duringcable pulling operation. In one embodiment, anti-rotation means can beprovided by providing means for slidably engaging piston rod 118 withshaft 119 such that rod 118 is inhibited from lateral rotation relativeto shaft 119. In one embodiment, illustrated in FIGS. 4-6, the internalsurface of rod 118 can include at least one groove or slot 172 extendingalong the longitudinal axis of rod 118. In another embodiment, aplurality of slots 172 are provided. In one embodiment, length of slot172 at least equals the distance rod 118 travels relative to the shaftposterior end 170 during piston operation. In another embodiment, slot172 extends the length of rod 118. Slot 172 can engage a protrusion,commonly called a ridge or key 174 extending perpendicularly from theouter surface of shaft 119 and dimensioned to fit in slot 172 and slidealong the slot path. As will be appreciated by those having ordinaryskill in the art, key 174 can be integral to shaft 119 or removablyattached by standard means. In the embodiment illustrated in thefigures, shaft 119 can engage with slot 172 by means of an anti-rotationkey or protrusion 174 extending perpendicularly from the surface ofshaft posterior end 170's axial opening 171. The anti-rotation key 174is dimensioned and positioned to fit in a slot 172, allowing rod 118 tomove along shaft 119's outer longitudinal axis while inhibiting lateralmovement of rod 118 relative to shaft 119. As will be appreciated bythose skilled in the art, shaft 119 is attached to housing 116, and theanti-rotation mechanism described herein also inhibits lateral rotationof rod 118 relative to housing 116.

In the embodiment illustrated in FIGS. 4-6, key 174 can be provided toshaft end 170 by means of a plate or annulus 176 which can be attachedto shaft end 170 by standard means. As will be appreciated by thoseskilled in the art, an anti-rotation key may be made integral to shaftend 170 rather than provided as part of a plate, and may even extendforward along the longitudinal axis of shaft 119's outer surface. Atleast one key-and-groove engagement pairing means are contemplated forproviding anti-rotation capability. A plurality of key-and-groove pairsalso are contemplated. In the embodiment illustrated in the figures,four pairs are illustrated, with four channels 172 distributed radiallyabout rod 118's internal surface, and anti-rotation keyed plate 176comprising four keys positioned about plate 176 to fit in slots 172. Asmaller or larger plurality of key-and-groove pairings also arecontemplated.

Single cylinder piston assembly 114 further can include an internalcable debris wiper or cable debris containment system 135 providingmeans for inhibiting debris that may be pulled into the shaft, forexample on the cable, from entering the piston rod cavity 139 andpossibly compromising one or more hydraulic seals such as seal 141.Internal wiper system 135 advantageously can be a telescoping system asillustrated in FIGS. 4-6, comprising a central channel dimensioned toreceive a cable and competent to continually span the distance betweenshaft 119 posterior end 170 and the posterior end of piston rod cavity139 during all phases of the piston stroke cycle. In the illustratedembodiment, wiper system 135 can include a substantially hollow firstwiper tube 180 having a posterior end that engages the posterior end ofpiston rod cavity 139, and dimensioned to fit within a larger secondwiper tube 186, which itself is substantially hollow and dimensioned tofit within shaft 119. Wiper tubes 180 and 186 preferably comprisehydraulic seals 184 and 190, respectively, to provide seals between (1)the outer surface of first wiper tube 180 and the inner surface ofsecond wiper tube 186, and (2) the outer surface of second wiper tube186 and the inner surface of shaft 119. Advantageously, seals 184 and190 can be associated with wiper tubes 180 and 186, respectively, bymeans of wiper caps 182 and 188, respectively, and which comprise agrooved or channelled perimeter on their outer surface into which seals184 and 190 fit. Optionally, seals 184 and 190 may be seated intochannels or grooves on the outer circumference of the anterior end ofwiper tubes 180 and 186. Useful seals include hydraulic seals well knownin the art, including, without limitation B-Lip polyseals and loadedU-cup seals.

Wiper caps 182 and 188 may be removably connected to their respectivewiper tube by any means known in the art. In the embodiment illustrated,connections include threaded coupling 191 and bolted coupling 192.Advantageously, a wiper cap may include a tool receiving surface 193 tofacilitate uncoupling the cap from the wiper tube. In the illustratedembodiment, first wiper cap 182 includes a tool receiving surface 193comprising a plurality of slots for receiving, for example, a spannertool to uncouple wiper cap 182 from first wiper tube 180.

Preferably, second wiper tube's anterior and posterior axial openingsdefine a lip 194 that extends out from the tube surface and piston shaft119's posterior axial opening also defines a lip 195 that extends inwardfrom its inner surface. Lips 194 and 195 are dimensioned such that shaftlip 195 contacts and holds piston lips 194 during directional movementof second wiper tube 186, preventing additional directional movement andretaining second wiper tube 186 within the shaft interior as piston rod118 pulls and recovers, and wiper system 135 telescopes in and out. Aswill be appreciated by those skilled in the art, the anterior lip 194 ofwiper tube 186 can be integral to tube 186 or can be provided or canproved by engaged wiper cap 188.

Similarly, the posterior axial opening of second wiper tube 186 alsopreferably includes a lip 196 extending inward along its innercircumference, and the anterior axial opening of first wiper tube 180comprises a lip 197 extending out from the tube outer surface. Lips 196and 197 are dimensioned such that second wiper tube lip 196 contacts andholds lip 197 during directional movement of first wiper tube 180,preventing additional directional movement and retaining first wipertube 180 within the second wiper tube 186 interior during the piston rodstroke action and wiper system 135 extension. As will be appreciated bythose skilled in the art, lip 197 may occur on first wiper tube body 180or cap 182.

In one embodiment, single cylinder piston assembly 114 also can includeholding gripper assembly 130 and pulling gripper assembly 137, each ofwhich includes a quick release mechanism. These assemblies are describedin detail below.

IV. Closed Path Dual Cylinder Piston Assembly

Turning now to FIGS. 7-8, a closed path dual cylinder piston assembly200 is described. Assembly 200 includes a housing 202 having a centerhole or channel 206 traversing the axial length of housing 202. Channel206 is substantially hollow and dimensioned to allow passage of a cable104 (not shown) therethrough. In one preferred embodiment, at least partof channel 206 is dimensioned to receive holding gripper assembly 130(see below).

Housing 202 further comprises two cavities 203 that flank centralchannel 206, each cavity dimensioned to receive a piston rod 204 throughan axial opening at the posterior end of housing 202. Cavities 203 flankcentral channel 206 and are equidistant therefrom, providing balanceddistribution of piston rod 204 weight within housing 202. In a preferredembodiment, cavities 203 does not extend all the way through housing 202and function as a piston barrel housing. As will be appreciated by thosehaving ordinary skill in the art, piston rods 204 advantageously mayinclude standard hydraulic seals 208 typically included in pistonoperation. Also as will be appreciated by those having ordinary skill inthe art, hydraulic connectors 198 include conduits within housing 202such that hydraulic fluid is provided to or expelled from both cylindersin tandem.

The closed path dual cylinder piston assembly 200 described herein iscompact and lightweight while still providing sufficient power to pullcable in a range of sizes through an underground space. Usual cablediameters can be, without limitation, in the range of about 10 mm to 22mm, or about ⅜-inch to ⅞-inch diameters. Bursting heads useful in thesystems disclosed herein can be for small diameter pipe (e.g., 1-3-inchbursting head) or larger (e.g., 4-inch bursting head or larger). In oneembodiment, piston assembly 200 accommodates piston cylinders in therange of at least about 1.5-inches to 3-inches. One useful pistoncylinder can include a 2-inch cylinder. In another embodiment, assembly200 can have an overall weight of less than about 50 pounds. In anotherembodiment, assembly 200 can have an overall length of less than about14 inches. In still another embodiment, assembly 200 can have an overallwidth of less than about 10 inches.

V. Holding Gripper Assembly

Dual Cylinder

Dual cylinder housing 204 further can accommodate a front holdinggripper assembly 130. In the embodiment illustrated in FIGS. 1, 2, 7 and8, holding gripper assembly 130 includes, from anterior to posteriorend: a gripper housing 212; a holding gripper 214 tapered at itsanterior end to define a cone, and preferably comprising a plurality ofsections or members 216 competent to compress together and expand apart;and a compression spring 218. Gripper assembly 130 further can define aninterior channel through which a cable can pass. In operation, thecompression spring 218 anterior end contacts the posterior end ofholding gripper 214 and rearward movement of gripper 214 compressesspring 218 against a backstop. When compression spring is extended,gripper 214 is pushed forward and onto a cable. The spring tensionsupports utility of the gripping system described in detail below aspart of a holding gripper assembly.

In one embodiment, the outer diameter of compression spring 218substantially matches the outer diameter of gripper housing 212. Inanother embodiment, a compression spring front cap 217 can be includedbetween compression spring 218 and the posterior end of gripper 214, andcap 217 provides the compressing contact with spring 218. In anotherembodiment, cap 217 can include an annulus with a central openingdimensioned to allow cable passage, and an outer diameter thatsubstantially matches spring 218 diameter, or slightly exceeds it. Inanother embodiment, cap 217 can be dimensioned to fit in piston cavity203. In another embodiment, cap 217 includes a lip that extends outperpendicularly from cap 217's outer circumference to create a boundedrecess into which the anterior end of spring 218 can fit.

Gripper housing 212 preferably defines a substantially hollow channeldimensioned to receive tapered holding gripper 214. The gripper housingchannel inner surface 220 preferably is tapered at its anterior end suchthat passage of the gripper 214 anterior end through the anterior end ofthe channel is inhibited. Gripper 214 can comprise multiple memberpieces or sections 216, typically between 2-4 pieces that fit togetherto define a hollow cone shape having an outer camming surface 225competent to engage the gripper housing tapered inner surface 220. Inthe embodiment illustrated herein, holding gripper 24 comprises threemember pieces 216. Member pieces 216 preferably have interior concavesurfaces 222 along their axial length that allow sections 216 to sit oncable 104 (not shown), the interior concave surfaces preferablycomprising barbs or ridges which further may be slanted such that whengripper sections 216 are compressed onto cable 104, the ridges gripcable 104 and prevent movement of the cable, such that gripper 214 actsas a clamping jaw or cable gripping jaw. In a preferred embodiment,gripper member pieces have a smooth outer camming surface, reducingfriction as the camming surface moves along the tapered interior surface220 of gripper housing 212.

In one embodiment, each gripper member 216 can contact its adjacentmember section through a joining member surface 219 on each member. Inone preferred embodiment, each joining member surface 219 can include amagnet 223 located to align with the magnet on the corresponding joiningsurface 219. In one embodiment magnet 223 can be embedded in the memberjoining surface such that it lies flush with the member joining surface.As will be appreciated by those having ordinary skill in the art, arange of magnet sizes and magnetic force may be used effectively in thedevices disclosed herein. In one embodiment, a useful magnet size is¼-inch by ¼-inch, although larger and smaller magnet sizes arecontemplated, including ⅜-inch (0.375-inch). In another embodiment, amagnet strength of N50 is used, also known as a rare earth or neodymiummagnet, and magnets of stronger and weaker strength also arecontemplated. A selected magnet strength will be competent to repel twoadjacent member joining surfaces from one another when the magnets arealigned and properly indexed. In another embodiment, the magnet canlocated at the balance point on the member joining surface. Otherpositions on member joining surface 219 also can be used for locatingthe magnet, provided the position selected is the same on each memberjoining surface. In another embodiment, magnets 223 on joining membersurfaces 219 are indexed so that the same pole (positive or negative) isexposed on each member joining surface 219 and the magnets repel oneanother when two member joining surfaces are joined and the magnets arealigned.

In the embodiment illustrated herein holding gripper 214 includes threemember pieces 216 and one magnet 223 per joining surface 219. It will beappreciated by those skilled in the art that more magnets could beutilized if desired. When used in the method described hereinbelow, themagnetized gripper members 216 can minimize undesired cable bindingduring the cable pulling process, and facilitate quick and easy cablerelease at the end of operations. In addition, magnetized gripper 214obviates the need for O-rings, bands, or other means currently describedin the art holding the gripper members together.

In one embodiment, useful springs of the present disclosure are in therange of about 1-inch to 5-inches in length. In another embodiment,useful springs are in the range of about 1.5-inches to −3-inches inlength. Preferred spring lengths will depend on the overall lengthchosen for the gripper housing inner surface 220, as well as theselected length of the gripper 214.

In one preferred embodiment, at least part of piston housing channel 206defines a cavity 224 at the piston housing channel 206 anterior end,cavity 224 having a larger diameter than channel 206 at its posteriorend. In one embodiment, cavity 224 is dimensioned to receive holdinggripper assembly 130. In one preferred embodiment, cavity 224 has anaxial length substantially equal to the axial length of the gripperhousing 212 cylinder and compression spring 218 in an uncompressed oronly partially compressed position. Advantageously, the posterior end ofcavity 224 (formed by the juncture of cavity 224 and channel 206) canact as a backstop for compression spring 218. It will be appreciated bythose skilled in the art that compression spring 218 may also include aspanner element, eg., at its posterior end to extend spring 218'soverall length.

In another preferred embodiment, means are provided for securing gripperhousing 212 to piston housing 202. In one embodiment, gripper housing212 can include a lip or edge 226 about its anterior axial opening,competent to lie flush against housing 202's outer front-facing surfaceand encircling the axial opening of cavity 224. When gripper housing 212is inserted in cavity 224, lip 226 provides attachment means forsecuring gripper housing 212 to piston housing 202. in one embodiment,attachment means can include threaded bolts or screws. Preferably,cavity 224 is dimensioned such that when spring 218 is compressed by,for example, pushing gripper 214 rearward, gripper 214 can fitcompletely within cavity 224 and when spring 218 extended, the anteriorend of gripper 214 can protrude at least partially through the anterioropening of gripper housing 212.

Single Cylinder

Similarly, and as illustrated in FIGS. 5 and 10, in a single cylinderpiston assembly 114 the anterior end of shaft 119 can define a cavity229 dimensioned to receive a front holding gripper assembly 130,described hereinabove. In one preferred embodiment, cavity 229 has alarger diameter than shaft 119 posterior channel 121. In anotherembodiment, the corner created by the juncture of cavity 299's posteriorend and shaft channel 121's anterior end can function as a backstop forcompression spring 218. In another embodiment, a disc or cap 217 havinga central opening dimensioned for cable passage can be included betweenthe gripper 214 posterior end and the compression spring 218 anteriorend. Disc 217 can serve to enhance contact between gripper 214 andspring 218. In the embodiment illustrated in FIGS. 5 and 10, lip 226 ofgripper housing 212 can fit into a channel or groove 136 about shaft endaxial opening 171 such that gripper housing 212 is recessed into cavity229 and its anterior end is substantially flush with the outer surfaceof piston housing 116.

VI. Holding Gripper Quick Release Manifold

Turning now to FIGS. 1, 2, 9A, 9B and 10, piston assemblies 114 and 200further can include a holding gripper manifold assembly 160. Manifoldassembly 160 can include manifold body 302 which further can include acentral axial opening 304 and opposing protrusions 306. Manifold bodyadvantageously can include means for coupling manifold assembly 300 tothe anterior end of a piston assembly, such as assembly 114 or 200.Useful coupling means can include, without limitation, bolt holes 303.Manifold protrusions 306 preferably are dimensioned to extend into andmoveably slide along side panel slots 146 of frame 110. During use,protrusions 306 may abut front ends of slots 146 to keep manifoldassembly 160 from sliding further forward relative to frame 110.Protrusions 306 also can include pin holes 307 that extend through theprotrusions. Pin holes 307 are dimensioned to receive pins 153 such thatmanifold pin holes 307 can be aligned with front pin holes 150 on frame110 for restaging a piston assembly during a cable pulling systemoperation as described below.

Manifold assembly 160 further comprises means for positioning holdinggripper 214 forward onto a cable surface (not shown), or for movinggripper 214 rearward and away from the cable surface, as desired. In onepreferred embodiment this positioning mechanism can include a piston 308that moveably couples with an insert 314 having an adjustable collar313. In one preferred embodiment, the coupling mechanism also transfersmotion so that as piston 308 couples with insert 314, piston 308 cancontact gripper 214 and move it rearward. In another preferredembodiment piston 308 is a threaded piston having external threads onits posterior end which couple with internal threads on the interior ofinsert collar 313. In another preferred embodiment, the threads onpiston 308 are multiple-lead or multiple-start threads, allowing greatertravel along the thread axis per piston rotation. For example, amultiple-lead thread can provide travel of 400/1000 inch with less than½ of a piston turn. Advantageously, multiple lead threads can providemore power and leverage through rotation than a single lead thread.Currently preferred are multiple-lead threads having 2 or more leads orstarts, more preferably having 3-6 leads.

Means for coupling piston 308 to insert 314 can be any means known inthe art. In the embodiment illustrated herein, piston 308 can beadvantageously coupled to insert 314 by means of a lever mechanism 310attached to piston 308. In use, manifold body 302 is provided to theanterior end of a piston assembly such as piston assembly 114 or 200with collar 313 of insert 314, dimensioned to fit inside manifold axialopening 304, inserted through axial opening 304 from the posterior endof manifold 302, and piston 308 inserted into collar 313 from theanterior end of manifold 302. Lever 310 then can be used to rotatepiston 308 rearward into insert 314. such that the posterior end ofpiston 308 contacts gripper 214 and moves it rearward by compressingspring 218 positioned posterior to gripper 214. In one embodiment,holding gripper assembly 130 is dimensioned such that when spring 218 isin a substantially extended (not compressed) state, gripper 214 canextend at least partially out of the anterior axial opening of thepiston assembly and into the axial opening defined by insert collar 313of insert 314. When gripper 214 is moved rearward out of the taperedcavity of gripper housing 212 by contact with threaded piston 308 andcompression of spring 218, the indexed magnets on gripper joining membersurfaces 219 repel member sections 216 away from one anothersufficiently that member sections 216 are held back and away from thecable surface. Member sections are stable in this position, bound in ondirection by the gripper housing cavity walls and in another directionby the repelling force of magnets 223. This spring compressed positionis referred to as an unlocked position, allowing cable to be threadedinto or out of piston assembly 114 or 200.

To put the cable into a locked position held by gripper assembly 130,lever 310 can be used to rotate piston 308 forward and away from insert314. This forward movement can decompress spring 218 and push gripper214 forward into the tapered cavity of gripper housing 212. Thedecompressing spring's forward movement provides sufficient force toovercome magnet 223's repelling forces and gripper members 216 arepushed forward and together, and forced down onto the cable surface bythe cavity's tapered inner surface 222. In one preferred embodimentmanifold body 302 can include a visual representation 340 indicatinglever positioning for the locked and unlocked position. One example of avisual representation is illustrated in FIGS. 9A and 9B.

In one preferred embodiment, threaded insert 314 can be removablyattached to the posterior end of manifold body 302. In one embodiment,attachment can occur by means of a lip 309 extending out radially fromthe posterior outer circumference of insert collar 315. In oneembodiment, lip 309 provides a surface for bolting insert 314 tomanifold body 302. In another embodiment, lip 309 is dimensioned to fitinto circular groove or recess 300 surrounding axial opening 304 on theposterior surface of manifold body 302, such that lip 309 lies flushwith the outer surface of manifold body 302 when threaded insert 314 isplaced in axial opening 304. In another preferred embodiment, means areprovided for adjusting the thread start position of insert 313 relativeto piston 308. In one embodiment, insert 315's thread start position canbe adjusted by means of one or more timing slots 317 on lip 309. In FIG.9 B, two timing slots 317 are depicted. As will be appreciated by thoseskilled in the art, a fewer or greater number of timing slots can beutilized advantageously. In another embodiment, insert attachment meansalso can include timing slot bolts 318.

Means also can be provided for removably coupling piston 308 to manifoldbody 302. Any means known in the art may be used to advantage. In oneembodiment, preferred coupling means also provide means for varying thestarting position or distance of piston 308 relative to threaded insertcollar axial opening 315. In one preferred embodiment, such means areprovided by removably coupling piston 308 to manifold body 302 by meansof one or more extensions 312, also known as stand-offs or stand-offpins. Stand-off pins 312 are configured about manifold body axialopening 304 and extend forward from the manifold body 302 in a planeperpendicular to the manifold body plane. Bolts 322 can thread intostandoff pins 312 and can attach piston 308 to pins 312. The distancepiston 308 enters manifold axial opening 304 can be modulated by varyingthe distance bolts 322 are screwed into stand-off pins 312. In onepreferred embodiment piston 308 is coupled to stand-off pins 312 bymeans of a bolting plate 320 which can couple to the anterior end ofpiston 308 and which further can include one or more protrusions 323extending out from the plate perimeter, and configured about theperimeter to align with stand-off pins 312. Bolting plate 320 furthercan include an axial opening 321 dimensioned to allow cable passagethere through. Bolting plate 320 can be coupled to piston 308 by anystandard means known in the art. In one embodiment, a hollow sleeve orbushing or other substantially hollow cylindrical spacer 319,dimensioned to fit through bolting plate axial opening 321 and intothreaded piston anterior axial opening 316, can be used to advantage. Inanother embodiment the outer surface of spacer 319 can include threadsfor aligning and coupling with threads on the interior surface of piston308's anterior axial opening 316. In another embodiment, spacer 319 canseat into a groove or channel in the piston 308 interior surface.Bolting plate 320 can couple to the anterior end of spacer 319 andattach both spacer 319 and piston 308 to manifold body 302. In theembodiment where spacer 319 threads into piston 308, further modulationof piston 308 positioning relative to manifold axial opening 304 isavailable.

A cable wiper also can be included in front manifold assembly 160 by anystandard means known in the art. Disclosed herein is an easy accesswiper assembly. An elastomeric wiper 324 is provided having an axialopening dimensioned to allow cable passage therethrough, the openingbeing sufficiently snug such that the axial opening inner perimeterwipes the cable surface as the cable passes through. In one embodimentwiper 324 can be dimensioned to fit on bolting plate anterior axialopening 321. In another embodiment a wiper cap 326 is provided forremovably coupling wiper 324 to bolting plate axial opening 321. In onepreferred embodiment wiper cap 326 can include an axial opening. Inanother preferred embodiment wiper cap 326 can include an interiorrecess configured about its axial opening and dimensioned to receivewiper 324. In another embodiment wiper cap 326 can have an outerdiameter dimensioned such that cap 326 fits on the bushing plate surfacesuch that the wiper 324 axial opening aligns with bushing plate axialopening 321. In still another preferred embodiment, wiper cap 326 caninclude one or more magnets that couple wiper cap 326, and associatedwiper 324, to bolting plate 320. In the embodiment disclosed herein,wiper cap 326 includes a substantially hollow shallow cylinder. Theinner surface of the wiper cap 326 cylinder includes a first channel 330configured to seat and hold wiper 324. The inner surface of wiper cap326 also can include a second channel 332 dimensioned to fit over thebolting plate 320 anterior surface. Second channel 332 can have a largerdiameter than first channel 330. In one preferred embodiment, theposterior end of wiper cap 326 includes one or more magnets embedded inits surface and competent to secure wiper cap 326 to bolting plate 320.In another preferred embodiment, wiper cap 326 includes a plurality ofrare earth magnets the number and strength of which are selected toprovide a secure fit, and also allow ease of removability withoutrequiring tools.

VII. Rear Pulling Gripper and Cable Release Latch Assembly

The ability of a gripper assembly to readily and reliably grab and pullcable during the piston pulling stroke and then release the cable so theattached piston rod can retract in a recovery stroke is a criticalfeature of useful cable pulling systems. Issues that can arise includegripper members binding to the cable surface and not releasing properlyduring the recovery stroke; and gripper members coming out of positionand not re-engaging effectively with the cable surface in a subsequentpiston pulling stroke. Referring to FIGS. 1, 2, 4, 5, 8 and 11-13, animproved rear pulling gripper and cable release assembly will bedescribed. The system has applicability for both single and dualcylinder assemblies.

Single Cylinder

In the drawings, rear pulling gripper and cable release assembly 138 canbe provided to the posterior end of single cylinder piston assembly 114or dual cylinder piston assembly 200. For ease of description, theassembly will be described first for a single cylinder piston assembly,and variations that can have applicability for a dual cylinder systemwill follow. As with all drawings in this disclosure, like-numberedparts reference like-membered components.

Rear gripper and cable release assembly 137 having utility for a singlecylinder assembly 114 can include a housing 402, which may include a topportion 404 and a bottom portion 406, wherein bottom portion 406 isattached to top portion 404 by any standard means, including, forexample, bolts 409 (see FIGS. 12C, 12D). If desired, positioning dowels407 also can be used to advantage. In another embodiment, top potion 404and bottom portion 406 may be a single integral unit. Housing 402further can include an axial opening 480 through which cable 104 (notshown) can pass. Housing 402 also can include an anterior end 400 and aposterior end 399. Posterior end 399 includes a quick release latchassembly described in detail below.

In the single cylinder system, housing 402 can be substantiallycylindrical in shape and dimensioned to fit through the posterior axialopening of piston rod 118 and into piston rod cavity 139 (see, e.g.,FIGS. 4B and 5). In one embodiment, housing 402 can be press-fit to thepiston rod 118 inner surface. In another embodiment, the outer surfaceof housing 402 can include a first cylinder portion 403 and a secondcylinder portion 401 posterior to first cylinder portion 403, with firstcylinder portion 401 having a smaller diameter than second cylinderportion 403 such that the two cylinder portions are stepped relative toone another. In this embodiment piston rod 118 can include acircumferential protrusion or shelf protruding from its inner surfaceinto cavity 139, to provide a girdle having an axial opening dimensionedto receive first cylinder portion 403 but not cylinder portion 401. Thepiston girdle and stepped cylinder portions 401 and 403 together canprovide additional points of contact between piston rod 118 and reargripper assembly housing 402, for additional support and stability ifdesired.

In the embodiment where single cylinder piston assembly 114 includes aninternal anti-rotation means, the annular perimeter of anti-rotationkeyed plate 176 can be dimensioned to fit into the outer surface steppedjunction between cylinder portions 401 and 403 (see, e.g., FIG. 5).

In another embodiment, housing 402 can include a third cylindercomponent 400 posterior to cylinder 401 and which includes a quickrelease latch assembly 129 described in detail below. The outer surfaceof third cylinder component 400 can have a diameter larger than secondcylinder component 401, such cylinder portions 400 and 401 are steppedrelative to one another the step or junction can act as a lip. Inanother embodiment, the outer perimeter of posterior cylinder portion400 can be dimensioned to substantially match the outer diameter ofpiston rod 118 such that cylinder portion 400 abuts the posterior end ofpiston rod 118 as a lip when housing 402 is inserted into piston rod118, providing points of contact for additional stability if desired.

Housing 402 can include an inner cavity accessible through axial opening480 and dimensioned to receive a rear pulling gripper 414. Gripper 414preferably comprises a plurality of member pieces 418 that fit togetherto define a hollow gripper having an inner surface 419 that defines anaxial hole or channel of a dimension and texture competent to engage apulling cable surface 104 (not shown) and bite into the cable. In onepreferred embodiment, the inner surface or channel 419 is threaded suchthat the threads act like teeth to bite into the cable and the cableclamping gripper 414 acts as a clamping jaw or cable gripping jaw. Inanother embodiment, gripper 414 includes two gripper member pieces 418.In another embodiment, member pieces 418 can include “square gripper”pieces. In another embodiment, member pieces 418 fit together to definea hollow, substantially triangular shaped gripper 414. In oneembodiment, gripper member pieces 418 can have a substantiallyright-angled shape and gripper 414 can have an isosceles triangularshape. In another embodiment, housing cavity 405 can include acorresponding triangular shaped cavity. In addition, the gripper 414outer surface and cavity 405 inner surface can include one or morecoupling or interconnecting means for guiding the axial directionalmovement of gripper member pieces 418 in cavity 405 during the cablepulling operation. In one embodiment, the interconnecting means can: (1)guide directional movement of gripper 414 forward during the pistonpulling stroke so gripper inner surface 419 can engage cable 104; and(2) guide directional movement of gripper 414 rearward during the pistonrecovery stroke so gripper inner surface disengages from cable 104. Useof a means for guiding gripper 414 in and out of position can improveefficient cable pulling function. Useful interconnecting means betweengripper 414 and cavity 405 can include one or more ribs and channels,keys and key plates, grooves and ridges, sleeves or slots and ribs, andthe like.

In one embodiment, gripper member 418 can include a ridge or key 422configured to fit into a channel or groove or key plate 410 in thehousing cavity 405 inner surface. In one embodiment, ridge 422 protrudesup from the top surface of gripper member 418, and groove or slot 410defines a directional channel in the top inner surface of cavity 405. Inanother embodiment, opposing outer lateral sides 413 of gripper 414 canfunction as ribs, configured to fit into opposing channels or slots 411in the left and right sides of the cavity 405 inner surface. In oneembodiment, the bottom of housing cavity 405 also can include a recessor channel 412 along its longitudinal axis. In another embodiment, thebottom inner surface of cavity 405 is substantially flat. As will beappreciated by those having ordinary skill in the art, variousconfigurations of interconnecting grooves or slots and rib or ridges orkeys can be configured to advantage, provided that the interlockingmechanism allows gripper 414 to travel unrestricted, and the path canmove gripper in and out of cavity 405. In addition, the selected slopeof the gripper 414 lateral sides and the cavity 405 lateral sides willdepend on the length of gripper 414 selected and the size of housingcavity 405.

Rear gripper assembly 137 also can include means for modulatingdirectional movement of rear pulling gripper 414 during pistonoperation. In particular, means can be provided for modulating thedegree of gripper member 418 rearward directional movement in cavity 405during a piston recovery stroke. In one embodiment rearward directionalmovement of gripper member 418 during a piston recovery stroke can bemodulated by a spring-loaded levering mechanism 427.

One embodiment of a spring-loaded levering mechanism 427 is illustratedin FIGS. 11-13. In the figures, pulling gripper 414 includes means forcoupling to a torsion spring that limits rearward movement of grippermembers 418. In one embodiment, gripper members 418 can include a pin426. In another embodiment, gripper member 418 can include a protrusionextending rearward from the member 418 lateral angled edge, and pin 426extends inward from the protrusion at a substantially perpendicularangle, toward the gripping surface of member 418. Pin 426 advantageouslycan provide means for a spring-loaded mechanism to removably attach togripper member 418. In one embodiment a spring-loaded mechanism can beprovided by a torsion spring 432. Torsion spring 432 can include aspring 433 typically flanked at its ends by torsion spring pins 434 andgrease zerks 436.

In one embodiment torsion spring 432 is coupled to a lever component 442that removably couples to gripper pin 426. In another embodiment levercomponent 442 is a substantially U-shaped member having two laterallyopposed arms 444 and 445, the arms being connected to one another bymeans of a bridging spanner 447. Each arm 444 and 445 can include meansfor removably catching or clasping or otherwise coupling to gripper pin426. In a preferred embodiment, the position of the catching means oneach arm and the distance between the arms of lever component 442 areconfigured such that each arm and its corresponding pin catching meansare aligned with a gripper pin 426. In one embodiment, gripper pincatching means 450 on lever arms 444 and 445 can include a hollow orrecess or slot in the lever arm that begins at the lever edge thatcontacts gripper pin 426 and extends at least partway into the lever armbody. In another embodiment, the hollow or slot 450 follows a lateralpath in from the lever edge and then curves downward substantially atleast 90 degrees for a distance. In still another embodiment, slot 450curves downward at least about 100 degrees. In another embodiment slot450 has vertical “kidney-shape” or “bean-shape” appearance. It will beappreciated by those having ordinary skill in the art that slot 450 caninclude a recess in the lever arm or comprise a complete cutout in thelever arm.

In another embodiment, torsion spring 432 can couple to lever component442 at bridging spanner 447. In particular, bridging spanner 447 canhave a substantially hollow interior and axial openings 443, dimensionedto receive torsion spring 432. To activate the torsion spring in levercomponent 442, at least one end of torsion spring 432 is attached to astationary surface and at least one end of torsion spring 432 alsoattaches to lever component 442. In a preferred embodiment both ends oftorsion spring 432 also attach to a stationary surface. In anotherpreferred embodiment, one end of torsion spring 432 attaches to bridgingspanner 447 of lever component 442. Pins 431 are exemplary means forattaching torsion spring 432. Once torsion spring 432 is attached asdescribed herein, movement of lever component arm 444 or 445 about thespring axis will have a spring-loaded tension.

In one embodiment, the stationary surface to which the torsion springand lever component 442 can attach advantageously can be a hinge block428. In one preferred embodiment, hinge block 428 can include twolateral opposing protrusions 438 extending rearward from the block anddefining a gap or slot 440 dimensioned to receive lever component 442and torsion spring 432. In another embodiment, hinge block protrusions438 also can include lateral openings configured to align with bridgingspanner axial openings 443 and through which torsion spring 432 can passto enter the bridging spanner hollow interior. As will be appreciated bythose having ordinary skill in the art, hinge block 438 can be anindependent unit that can be removably coupled to rear assembly housing402 as illustrated here, or it can be an integral element of housing402. Where hinge block 438 is an independent component it can beattached to housing 402 by any standard means known in the art, such asby bolts 431. In one preferred embodiment, hinge block 438 can fit intoa recess or gap in housing 402 posterior end so that the overallcylindrical shape of housing 402 and cylinder component 400 ismaintained.

During cable pulling operation, the piston rod 118 pulling stroke pullsthe attached rear gripper housing 402 rearward, and rear gripper members418 are pulled forward along their grooved or keyed pathways into thehousing tapered cavity and onto the cable surface. Lever gripper pinslots 450 are engaged with gripper pins 426 and lever arms 444 and 445are in a vertical position with little or no torsion on torsion spring432. During the piston rod recovery stroke, piston rod 118 moves forwardalong with attached gripper housing 402, moving housing tapered cavityaway from gripper 214, and gripper members 418 are free to move rearwardalong their channelled or keyed pathways and off the cable surface. Asgripper members 218 move rearward, gripper pins 246 move along the pathof engaged pin slot 450, pushing the corresponding lever arm rearwardand engaging the torsion action of torsion spring 432. Engaged torsionaction allows lever arms 444 and 445 to modulate the speed and distanceattached rear gripper members travel rearward during the recovery strokeand keep them substantially in position for travelling forward againalong their keyed paths and re-engaging again with the cable surfaceduring the subsequent power stroke.

The rear pulling assembly described herein works in tandem with holdinggripper system described above for pulling cable through a pistonassembly. In particular, when piston rod 118 is traveling rearwardduring the power stroke, attached rear gripper housing also travelsrearward forcing gripper 414 further into the taper cavity and onto thecable surface. The rearward pulling action on the cable pulls frontholding gripper 214 rearward and out of its tapered cavity, so cable isfree to move rearward. During the piston recovery stroke, attached reargripper housing 402 travels forward, releasing gripper 414 from thetapered cavity and off the cable surface. This action allows cable toslide forward, which pushes front holding gripper forward into itstapered cavity and back onto the cable surface to hold the cable untilpiston rod 118 begins its next power stroke.

A latching mechanism now will be described for easily releasing reargripper 414 from gripper assembly 137. Once the cable pulling operationis complete, the cable needs to be disengaged from the pulling system100. This process requires ensuring rear gripper 214 is off the cablesurface and out of the way when the cable is extracted. The latchingsystem described hereinbelow provides a quick, simple and reliable meansfor: (1) ensuring rear cable gripper members 218 are disengaged from thecable surface, and (2) removing gripper members 218 from the assemblywithout requiring additional tools. Means are provided for releasinglever slot 450 from gripper member pin 426 and holding lever 442 in anopen, disengaged position so that rearward movement of gripper members218 is no longer modulated or inhibited. In this position, grippermembers move freely rearward along their keyed or channel paths andslide rearward at least partially out of housing cavity 405 where theycan be accessed and removed. In one embodiment lever slot 450 can bereleased from gripper pin 426 by means of a latching mechanism thatengages lever 442.

In one embodiment a latch 458, attached to housing 402, is configured toremovably engage with at least one arm, referred to herein as triggerarm 444, of U-shaped lever 442. In one preferred embodiment latch 458can rotate about its attachment axis. It will be appreciated by thosehaving ordinary skill in the art that either arm 444 or 445 can beconfigured as the trigger arm. Also as will be appreciated by thosehaving ordinary skill in the art, many standard means for attachinglatch 458 to housing 402 are known and include, without limitation, athumb screw or shoulder bolt 448 and O-ring. In another preferredembodiment latch 458 is attached to the housing 402 outer surface on itsposterior face, at a location above housing cavity 405. In anotherpreferred embodiment, the outer surface of housing 402 can include aslot or gap 472 having a side wall to which latch 458 is attached, andfront wall 474 that latch 458 can be rotated to and stored when not inuse. In another embodiment front wall 474 can include a forward-angledor beveled surface. In another embodiment trigger arm 444 can have alength sufficient to extend up to latch 458 attached to housing 402 sothat latch 458 can couple with and engage a pin 462 on a surface oftrigger arm 444. In another embodiment, trigger arm 444 can include oneor more indentations 452 configured for easy gripping.

Housing surface gap 472 also can be configured to include a recess intowhich trigger arm 444 can pass when piston rod 118 is retracted intopiston assembly 114. In another preferred embodiment, latch 458 caninclude a slot or hollow or groove 472 dimensioned and configured tocatch or clasp or otherwise removably couple trigger arm latch pin 462.In another embodiment latch slot 472 can engage pin 462 when latch 458is rotated into a substantially horizontal position and trigger arm 444is at least partially extended. In another embodiment, latch slot 472includes an angled path sufficient to hold lever pin 462 engaged andtrigger arm 444 in an open, extended position in spite of the torsionimposed on trigger arm 444 by torsion spring 432 to return to a verticalposition. In this position, gripper414 is free to move rearward itschannelled path and out of cavity 405.

In the embodiment illustrated herein, lever arm 444 is the trigger armand includes latch pin 462 on its interior lateral surface. Latch 458 isattached to the left lateral wall of slot 472 on housing surface 402,when viewing the assembly rearward. In the illustrated embodiment, latchslot 458 is configured on the interior lateral surface of latch 458. Aswill be appreciated by those having ordinary skill in the art, otherconfigurations of trigger arm 444 and latch 458 are contemplated and arewithin the skill of the art to create, given the present disclosure.

Dual System

As is evident from the figures, the rear gripper assembly mechanism andcomponents are substantially the same for both a single and dualcylinder piston assembly. Dual cylinder piston rear gripper assemblyhousing 402 can include an anterior end 400 and a posterior end 399. Inone embodiment, anterior end housing section 400 can include laterallyopposed protrusions 484 dimensioned and configured to fit into andmovably slide in frame side panel slots 146.

VIII. Small Diameter Pipe Extraction Chassis

In some instances existing underground pipe can slide out with the cableduring the cable pulling process and into the exit pit where the cablepulling system is located. This is particularly evident when smallerdiameter pipes, such as 2-inch or 1-inch water or electrical pipes arebeing replaced. When existing pipe gets co-extracted or co-extruded, itneeds to be removed from the cable exit area so that it does notinterfere with the cable pulling process. Typically, an operator standsby and cuts or splits the extracted cable. This process can becumbersome, slow and dangerous for an operator. When the cable pullingsystem includes a laterally positioned piston assembly positioned at thecable exit site in the pit, effectively removing extruded pipe can bedifficult.

A pipe extraction chassis and cable pulling system are disclosed hereinthat (1) keeps the piston assembly elevated, in a substantially verticalposition, away from the cable exit opening during the pulling operationand without the need for bolting the assembly into position, and (2)splits extracted or extruded cable as it exits the ground, withoutrequiring operator participation. Other advantages of the pulling systeminclude that it provides an adjustable chassis whose length can bevaried according to desired pit dimensions, and it does not requirebolting of the piston assembly to the chassis to hold the pistonassembly in place. The system is compact and easy to use in smallspaces. While the pipe extraction chassis and cable pulling systemdisclosed herein has particular application when small diameter pipe,such as, for example, 2-inches or less, is being replaced, those skilledin the art will appreciate it has utility in any application whereunderground pipe may be extracted during a cable pulling or replacementpipe operation and may need to be split.

Referring now to FIGS. 14-16, a pipe extraction pulling system 500 isshown. The system 500 can include a cable pulling apparatus 502 whichcan pull cable 104 and an attached bursting head and replacement pipe(not shown). The pipe extraction cable pulling apparatus 502 can includea piston assembly 111 and pipe extraction chassis 504. In the embodimentillustrated, the piston assembly is a closed path dual cylinder assembly200. Chassis 504 provides an adjustable frame for holding a pistonassembly away from the cable exit. Pipe extraction chassis 504 caninclude faceplate 506, a back plate 509, side braces 512, and supporttruss plate 510, which components can be removably coupled with bolts519. Faceplate 506 can include an opening 508 through which a cable, abursting head or any extracted pipe (not shown) can pass. Backplate 509also can include an opening 513 configured to align with faceplateopening 508 and through which at least a cable can pass. The length ofside braces 512 can be selected to provide a desired open space intowhich split extracted pipe can accumulate (see below). The open spacealso can be used for bursting head and cable disengagement. The heightof pipe extraction chassis 504 can be any desired height, providedsufficient clearance is maintained for functional cable pullingoperation. Those having ordinary skill in the art can readily select apreferred height provided with this disclosure and the particulars oftheir cable pulling operation. In one embodiment, a useful pipesplitting chassis height can be in the range of less than about24-inches. In another embodiment, useful height ranges can include about14-20 inches. In another embodiment, useful pipe splitting chassiswidths can be in the range of about 10-16 inches. In another embodiment,useful lengths can be in the range of about 16-30 inches. In anotherembodiment, a pipe splitting chassis 504 can have a weight of less thanabout 60 lbs.

Truss plate 510 can be dimensioned to provide additional support forframe 504 and to provide means for holding a piston assembly and cablepulley mechanism. Truss plate 510 can include a floor plate 518 and twolaterally opposed vertical front braces 503 that can attach to backplate509. A pulley mechanism 525 can be included on two laterally opposedside braces 516. In one embodiment side braces 516 have an angled ortapered width to reduce weight and for ease of handling. A lateralsupport bar 520 also can be included that spans the distance betweenside braces 516. Pulley mechanism 525 can include pulley 526 and pulleyaxle 528 dimensioned to pass through a central axial opening in pulley526. Pulley mechanism 525 can be included on frame 504 by attaching tothe inner-facing lateral surfaces of side braces 516 by standard meansknown in the art. In one embodiment, pulley mechanism 525 can beattached by means of bushing 530 which attaches to side brace 516 atopening 532 and couples to pulley axle 528. Depending on the dimensionsof the pulley selected and its proximity to back plate 509, it can bedesirable to include clearance for pulley 526 by creating an opening inbackplate 509. In the illustrated embodiment, backplate opening 513includes a keyhole-shaped opening, the upper portion of which isdimensioned to accommodate pulley 526.

In one embodiment, the vertical height of front brace 503 is greaterthan attached side brace 516 such that the top edge of side brace 516and front surface of front brace 503 form a shelf 522 dimensioned toreceive and hold a piston assembly. In another embodiment, the top edgeof side brace 516 can be angled to hold the piston assembly at an angle.Seating the piston assembly on shelf 522 having an angle less than 90degrees can allow gravity to assist holding the assembly in placewithout the need for bolts or other attachment means that require toolsto engage or disengage. Useful angle ranges for shelf 522 can be in therange of about 10-45 degrees. In one embodiment, the piston assemblyincludes dual cylinder assembly 200 and shelf 522 has an angle of in therange of about 15 degrees. As will be appreciated by those havingordinary skill in the art, useful shelf angles can vary depending on thepiston assembly chassis dimensions selected, cable diameter, and chassisdimensions, for example. The piston assembly further can be removablyheld in place by cylinder assembly dowels 524 dimensioned and configuredto access aligned openings 523 in the piston assembly. In one embodimentdowel openings 523 can be provided through the bottom surface of frontgripper assembly manifold body 302. In the embodiment illustratedherein, dowel openings 523 advantageously can be provided through thebottom surface of laterally opposed front manifold protrusions 306 inpiston assembly 200. It will be appreciated by those having ordinaryskill in the art that other means of slidably interlocking orinterconnecting a piston assembly to frame 504 are within the scope ofthe present disclosure. For example, piston assembly shelf can includeside walls or side channels that accommodate manifold protrusions 302 orgrooves or ridges made therein. Once the assembly and cable are inplace, the cable pulling operation itself also can assist in holding thepiston assembly in place due at least in part to the tension on thecable. In one embodiment, the lateral edges of pulley 526 can bebevelled, which can assist cable in staying in the pulley groove duringthe cable threading process at the start of a cable pulling operation.

Pipe extraction system 500 also can include a pipe splitter 534assembly, illustrated in detail in FIGS. 20A and 20B. In one embodiment,pipe splitter assembly 534 includes means for splitting extracted pipeas it is extruded from a tunnel underground. Assembly 534 can include anaxial opening dimensioned to allow passage of a cable therethrough, butnot the extruded or extracted pipe. Pipe splitter assembly 534 alsopreferably can include means for easily engaging and disengaging thepipe splitter from the pipe extraction chassis without requiring tools.

Pipe splitter assembly 534 can include a pipe splitter 535 andattachment plate 542. Pipe splitter 535 can include a body 539 which canbe substantially cylindrical in shape and can include a substantiallyhollow interior. Axial opening 537 is dimensioned to allow passage of acable therethrough. Pipe splitter nose 536 can be dimensioned to fitinside the axial opening of an extruding pipe and guide it back towardsone or more pipe splitting blades 538 disposed radially about the outercircumference of body 539. As cable is pulled rearward through pipesplitter axial opening 537, pipe splitter nose 536 can enter the axialopening of any extracted pipe that may accompany the cable. The rearwardmoving extruded pipe can be guided back along the outer surface of pipenose 536 where blades 538 cut the rearward moving pipe. In oneembodiment two blades are provided and the extruded pipe is split intotwo sections that splay out and away from the pipe splitter while theinterior cable continues its rearward movement. In one embodiment nose536 can have a tapered or angled outer surface, tapering towards axialopening 537. In another embodiment pipe splitter 535 can include aplurality of blades. In still another embodiment, the plurality ofblades can be in the range of about 2-6. In the illustrated embodiment,two blades 538 are used to advantage. Those having ordinary skill in theart will appreciate that a greater or fewer number of blades also can beused to advantage, depending on the application and the diameter andtype of extruded pipe to be split.

Pipe splitter 535 can be advantageously coupled to a surface by means ofsplitter attachment plate 542. Attachment plate 542 can include boltholes 544 and an axial opening 543 configured to align with theposterior axial opening 537 of splitter body 539 such that cable beingpulled through pipe splitter 535 can pass through attachment plate 542.In one embodiment, pipe splitter 535 can be fit into grooves or channels546 in attachment plate 542 that are configured to fit distal ends ofblades 538 and splitter body cylinder 539 such that axial openings 537and 543 are aligned and pipe splitter 535 extends perpendicularly out ofthe plane of attachment plate 542. In one embodiment, pipe splitter 535can include two blades 538 laterally opposed from one another aboutsplitter body 539 and coupling groove 546 can include a grooveencircling axial opening 543 and extending out therefrom in twodirections that are 180 degrees opposed. In another embodiment, splitter535 can be held in position on attachment plate 542 by means of one ormore magnets 540 competent to attract and hold a metal portion ofsplitter 535. In still another embodiment, magnets 540 can be embeddedin recesses 550 on attachment plate 542 such that they are flush withthe attachment plate surface. At least one magnet can be used to holdsplitter 535 to plate 542, and a plurality also are envisioned. In theembodiment illustrated here, two magnets 540 are used. As will beappreciated by those having ordinary skill in the art the number ofmagnets selected will depend on the magnetic strength desired and thesize and weight of the pipe splitter assembly, all of which can bedetermined without undue experimentation provided with this disclosure.Attachment plate also can include one or more openings 548 that canreduce plate weight and enhance maneuverabilty, and also means for splitpipe sections to pass if desired.

IX. Rear Cable Release Pipe Bursting Head

Provided herein and illustrated in FIGS. 17-22 are improvements in smallbursting head devices (suitable for 2-inch pipe diameter or less) andlarge bursting head devices (suitable for 3-inch pipe diameter or more).In these drawings, the tapered nose cone of a bursting head isdesignated as the forward or proximal end, and this same orientationapplies to the bursting head components described hereinbelow. Thebursting heads described herein share many of the features andadvantages of the bursting head devices disclosed in US 2014/0241812,and include additional improvements to that disclosure. In particular,the devices disclosed herein provide an integrated cable gripping andrelease assembly 600 and mechanism. In one embodiment no tools areneeded to operate the integrated mechanism.

Referring first to FIGS. 17 and 18, two exemplary embodiments of anintegrated cable clamping and release assembly 600 are illustrated for alarge bursting head (FIG. 17) and a small bursting head (FIG. 18),respectively. Assembly 600 can include an integrated clamping jaw 601comprising a cable gripper component 602 at its proximal end, and aplunger component 604 at its distal end, interlocked with cable grippercomponent 602. Integrated clamping jaw 601 also can include a centralcavity 624 with an axial opening, and dimensioned to allow cable passagethrough cable gripper component 602 and into plunger component 604. Inone embodiment cable can be fed into integrated clamping jaw 601 throughaxial opening 614 at the proximal end of cable gripper component 602. Inone embodiment cavity 624 is closed at its distal end, and can provide abackstop for a free cable end. In another embodiment, cavity 624 caninclude a channel with an axial opening at its distal end, and a plug orscrew 628 threaded into the distal axial opening can function as a cablebackstop. In another embodiment, screw 628 can provide attachment meansfor a replacement pipe attachment mechanism. In one embodiment, the pipereplacement mechanism can include a clevis 632 and clevis pin 634. Inanother embodiment, screw 628 is a swivel screw and attachment to clevis632 allows free rotation of clevis 632 about the screw axis.

Integrated cable clamping and release assembly 600 also can includemeans for moving integrated clamping jaw 601 forward or rearward in abursting head along the bursting head's longitudinal axis so as to movecable gripper component 602 on or off a cable surface as desired. In oneembodiment, integrated clamping jaw 601 longitudinal movement means canbe provided by a backplate 608 configured to fit into the distal end ofa bursting head cone 647 and to which integrated clamping jaw 601 cancouple (see, e.g., FIG. 19). In another embodiment, integrated clampingjaw 601 longitudinal movement means can be provided by an endcap 605configured to fit into the distal end of a bursting head cone 647 and towhich integrated clamping jaw 601 can couple (see, e.g., FIGS. 20-21).In another embodiment particularly useful for small diameter burstingheads, endcap 605 can also function as a pipe replacement mechanism andcan include a clevis 632.

In the embodiment where the means for moving integrated clamping jaw 601forward or rearward in a bursting head is provided by backplate 608,coupling means can include coupling plunger component 604 to backplate608. In another embodiment, backplate 608 has a central cavity 609dimensioned to receive plunger component 604, and coupling means caninclude removably coupling the external surface of plunger component 604with the inner surface of the backplate 608 cavity. In one embodiment,plunger component 604 can include external threads 623 that can couplewith threads 625 on the inner surface of the backplate 608 cavity suchthat rotation of the plunger about its longitudinal axis will moveintegrated clamping jaw 601 forward or rearward, relative to backplate608. The choice of thread form and thread direction can readily bedetermined by those having ordinary skill in the art. For example, forbursting heads where high strength may be desired, trapezoidal or Acmethread forms may be used to advantage. In addition, as will beappreciated by those skilled in the art, the preferred thread directionchosen will depend on the handedness of the lay cable selected.Preferably, the selected thread direction is the opposite of the cablehandedness, to inhibit the natural tendency of cable to unwind during acable pulling operation. Where a right-handed lay cable is used, forexample, plunger external threads 623 can advantageously be leftthreading.

In the embodiment where the means for moving integrated clamping jaw 601forward or rearward in a bursting head is provided by endcap 605 (FIGS.18, 21-22), coupling means can include coupling plunger component 604 toendcap 605, preferably by threading plunger 604 into a threaded cavityin endcap 605 such that rotation of plunger 604 about its longitudinalaxis will move integrated clamping jaw 601 forward or rearward, relativeto endcap 605.

Integrated cable clamping and release assembly 600 movement means alsocan include an integrated element 630 that can be accessed by anoperator to initiate longitudinal movement of clamping jaw 601 throughbackplate 608. In one embodiment, illustrated in FIGS. 17 and 19,integrated element 630 comprises a handle attached to the distal outersurface of plunger component 604. As will be appreciated by those havingordinary skill in the art, handle means are well characterized in theart, and a variety of suitable handles are contemplated and can be usedto advantage provided with the present disclosure. In one embodiment, aprotrusion or stem 670 can extend out from the distal end of plunger 604and the handle means can be attached thereto. In the illustration, thehandle means can include one or a plurality of spurs 666 that extendradially out from the outer surface of stem 670. In the figure, sixspurs are provided, and a fewer or greater number also are contemplated.In another embodiment, spurs 666 can attach to plunger stem 670 by meansof an annulus or cuff 668 having an inner circumference dimensioned tofit over the outer surface of plunger stem 670. In this embodiment,spurs 666 can extend radially from the outer surface of cuff 668. Inanother embodiment, cuff 668 can be press fit onto stem 670.

In another embodiment, integrated element 630 can include a receivercomponent 631 for a manually attachable handle. Use of a manuallyattachable handle can be advantageous for smaller diameter bursting headdevices. In one embodiment, the receiver component 631 can include a hexscrew that attaches to the distal end of plunger 604 or a plunger stem670, and the manually attachable handle can include a key or allenwrench. Other manually attachable handles and handle receivers also arecontemplated and are within the skill of the art to use, provided withthe present disclosure.

As illustrated in FIG. 22, forward movement of clamping jaw 601generally will be limited by contact of the gripper component taperedouter surface 616 with bursting head tapered inner surface 650.Integrated cable clamping and release assembly 600 also can include astop ring 612 which functions to limit rearward movement of clamping jaw601 in the bursting head. In one embodiment stop ring 612 can be anintegral element of plunger component 604. In another embodiment,illustrated in FIGS. 17 and 19, stop ring 612 can comprise anindependent element that includes a central axial opening dimensioned tofit over the outer surface of the plunger component 604 proximal endsuch that the inner circumference of stop ring 612 engages with a stopring engaging surface 611 on at least a portion of the plunger component604 outer surface. In another embodiment, engagement between stop ring612 and the backstop engaging surface 611 on plunger component 604 canoccur by mechanical coupling means, including by threading, for example.While threading is a preferred mechanical coupling means, those ofordinary skill in the art will appreciate that other coupling meansknown in the art could be used to advantage, provided with the presentdisclosure. Mechanical coupling of stop ring 612 to integrated clampingjaw 601 can allow an operator to vary the longitudinal travel distanceof the integrated clamping jaw in a bursting head device. In anotherexample, the outer surface of stop ring 612 can include a groove orchannel 641 or other means for receiving a seal.

As will be appreciated by those having ordinary skill in the art,plunger component 604 can include a spacer section 607 between the backplate coupling means at its distal end and the gripper interlockingmeans at its proximal end. Spacer 607 can provide an additional meansfor modulating the longitudinal distance integrated clamping jaw 601 cantravel. The length of spacer 607 will depend on the dimensions selectedfor other components of the bursting head device, including othercomponents of the integrated cable gripping and release assembly. Spacer607 can include a stop-ring engaging surface, as illustrated in FIGS. 17and 19.

Gripper component 602 can comprise a plurality of member pieces 610 thatare configured and function as sections 216 of holding gripper 214,described above. Key features include a tapered camming outer surface616 that can engage a gripper housing tapered inner surface, in thiscase of a bursting head cone 650 (see FIG. 22); an interior concavesurface 613 with barbs or ridges or teeth that can grip a cable; andaligned magnets 618 on each joining member surface, each magnet indexedsuch that adjoining magnets repel each other when two member joiningsurfaces are joined and the magnets are aligned. Gripper sections 610further include means at their distal end for interlocking the proximalend of plunger 604 such that gripper component 602 and plunger 604behave as a single unit 601 throughout the cable pulling operation,particularly with respect to longitudinal movement of clamping jaw 601.

One embodiment of an interlocking means that can engage grippercomponent 602 and plunger component 604 of clamping jaw 601 isillustrated in FIGS. 17-21. In the example, the distal inner surface ofgripper sections 610 can include a channel or groove 620 dimensioned tofit and interlock with a lip 622 extending laterally out from theproximal axial opening of plunger component 604. When gripper sections610 come together to form gripper component 602, grooves 620 togetherform a recessed ring or channel around the interior circumference ofgripper component 602.

One advantage of integrated clamping jaw 601 is that unintended orundesired longitudinal rearward movement of gripper component 602 duringthe cable pulling operation is substantially prevented as may happen,for example, due to an unanticipated jarring or jerking event to thebursting cone. This may occur for example, when a bursting headencounters an open lead joint. In prior art bursting heads, such anevent could allow one or more gripper sections to momentarily move backand off the cable by, for example, causing a spring distal to thegrippers to compress. When the gripper sections subsequently re-engagewith the cable surface, cable alignment with the spring or the grippersections could be altered and could impact efficiency of the cablepulling process. This undesired consequence is obviated by the presentimprovement which stabilizes and holds gripper section longitudinalpositioning substantially immobile throughout a cable pulling operation.

Assembly and operation of the integrated cable gripping and releaseassembly in a bursting head device now will be described. An example ofa 4-inch bursting head device is depicted in FIGS. 17, 19 and 22, and isrepresentative of larger bursting head devices.

In one embodiment, spurs 666 can be attached to a cuff 668 and thisassembly can be press fit onto a plunger stem 670. A replacement pipeattachment means 632 can be fit to the distal end of plunger 604 or stem670 by providing screw 628 to replacement pipe attachment means 632through plunger cavity 624 and distal axial opening 671 and threading itinto a proximal opening in replacement pipe attachment means 632.Particularly where pipe attachment means 632 includes a clevis that canswivel about attached screw 632 inclusion of a grease zerk 636 can beadvantageous. If desired, a pliable cable stop member 626 also can beprovided to plunger cavity 624, proximal to screw head 628. Cable stopmember 626 can be made out of rubber or a flexible polymer, and canprovide a cushion that absorbs impact to the cable end during operation.Plunger 604 then can be threaded into back plate 608 and stop ring 612can be located at a desired position on plunger stop ring receivingsurface 611 (and plunger spacer). Plunger lip 622 then can be set ingripper section groove 620. Advantageously, magnets 618 can hold grippersections 610 together, slightly out of alignment with one another, forease of insertion into the bursting head cone 647. Once inserted intocone 647, the tapered interior of the cone (see below) can force thesections into alignment.

Bursting head cone 647 has a tapered outer shape, where the proximal endis dimensioned to fit inside a pipe to be burst, and the distal end isdimensioned to exceed the pipe diameter so that, as the bursting head ispulled through the pipe, the distal end of bursting head cone 647 burstsor breaks apart the pipe. Bursting head cone 647 also can include one ormore pipe splitting blades 643 that can removably attached to the cone'souter surface with, for example, screw 644. In one embodiment blades 643can fit in one or more blade grooves 642 configured on the cone 647outer surface. In another embodiment, blades 643 can be integral to thecone head outer surface.

Cone 647 also can include an axial opening 648 through which a free endof a cable to be pulled can pass, and can include an internal cavity 652dimensioned to receive the integrated gripper and release assemblydescribed. In particular, bursting head cone 647 includes a taperedcavity dimensioned to accommodate gripper component 602, the innersurface 650 of the tapered cavity providing a camming surface forgripper section tapered outer surface 616, and the angle of the taperedcavity being sufficient to align the gripper section joining members andsubstantially inhibit their forward movement. Distal to gripper cavity652 are: cavity 656 dimensioned to receive plunger 604; cavity 658,dimensioned to receive stop ring 612; cavity 662, dimensioned to receivea seal; and cavity 660, dimensioned to receive backplate 608. In onepreferred embodiment, cavity 660 is dimensioned such that backplate 608is recessed in cone head 647. In another embodiment, cavity 660 isdimensioned such that both backplate 608 and integrated handle element630 are recessed in cone head 647. Bursting head cone 647 also caninclude means 664 for bolting backplate 608 to the cone. Bursting headaxial opening 648 also can include a channel or cavity 654 dimensionedto receive one or more O-rings 646 to inhibit entry of debris or liquidinto the bursting head cone interior.

Once the assembly described above is inserted in cone 647, backplate 608is bolted into the cone at bolt positions 664. Integrated clamping jawmovement means handle 630 can be turned in the appropriate direction tomove clamping jaw 601 as far back as stop ring allows so cable can beinserted. In this position, gripper members are pulled back from theproximal end of taper cavity 652 and aligned magnets 618 repel joiningmember surfaces 619 away from each other and off the central axis,allowing a cable to be threaded into the cavity. Handle 630 then can beturned to move clamping jaw 601 forward until the front end of taperedcavity 652 prevents further forward movement. In this position, grippersections 610 are forced down onto the cable surface. The cable pullingoperation now can begin. At the end of the operation, handle 630 canagain be turned to pull plunger component 604 and interlocked grippercomponent 602 back, creating space for magnets 618 to repel joiningmember sections 610 away from each other and off the cable surface, andcable can be released.

Assembly of an exemplary 2-inch bursting head is illustrated in FIG. 20,and assembly of an exemplary 1-inch bursting head device is illustratedin FIG. 21. In these examples, replacement pipe attachment means 632 canbe a clevis, which may or may not swivel. As described above, in theseembodiments replacement pipe attachment means 632 is integral to endcap605, and endcap 605 also provides the longitudinal movement means forintegrated clamping jaw 601. The distal end of plunger component 604 canbe threaded into the cavity of endcap 605, and plunger lip 622 can beinterconnected with gripper sections 610 by means of grooves 620. Thisassembly then can be inserted into bursting cone head 647, which has asubstantially hollow tapered interior, providing substantially the samefunction as tapered cavity 652 in FIG. 22. The assembly can be securedby means of a backplate 608. Backplate 608 can be bolted into positionas illustrated in FIG. 20, or can be integral to endcap 632 and, forexample, threaded into or otherwise couple with, bursting cone 647, asillustrated in FIG. 21. Bursting head cutting blades 643 can be integralto the cone body (FIG. 21) or removably attached (FIG. 20). In theseembodiments longitudinal movement of clamping jaw 601 can be initiatedby means of an integrated element 630 accessible from the distal end ofendcap 605 and associated with plunger 604. In these examples,integrated element 630 includes a receiver 631 having an outer,engagable surface accessible from the distal end of endcap 605.

X. Sealed Cable Ends

In the operation of cable pulling systems and pipe replacementoperations it can be advantageous to provide cables with a sealed freeend. One advantage of such cable is that the sealed free end facilitatescable threading, for example into a bursting head. Another advantage isthat the sealed end inhibits the tendency of a cable end to fray, unwindor otherwise have its structural integrity compromised as a result ofuse. In the art, free cable ends can be sealed by, for example,crimping, cauterizing or soldering. Disclosed herein is a sealing methodhaving particular advantage in cable pulling operations. Advantages ofthe sealed cable ends provided herein include ease of manufacture,sealed end uniformity, enhanced strength and durability, and provide fora fabricator to form a cable seal with a desired dimension and shape.

5. FIGS. 23A and 23B illustrate one embodiment of a free cable end seal720. In the method, an outer edge of a cable free end 700 is cut away toexpose a stem 702, having a smaller diameter than that of cable body701. In one embodiment, the stem can be exposed by girdling the cableperimeter at a desired position distal to the cable end, therebyremoving a portion of the cable outer perimeter to reveal the stem. Acuff 704, having a substantially hollow interior dimensioned to receivestem 702, then can be placed on the cable end by inserting stem 702through the cuff's distal axial opening 706. Melted solder or otherliquid bonding material then is provided to the cuff/cable interface 714to secure cuff 704 to stem702. In one embodiment, melted solderinfiltrates interface 714 and cuff distal axial opening 706 to penetratethe cuff interior, providing solder to at least part of stem 702 and theinterior cavity of cuff 704 and securing stem 702 to the cuff interioras the solder cools. In another embodiment, solder penetrates the lengthof the cuff interior cavity.

One embodiment of a cuff 704 is illustrated in the figure. As will beappreciated by those having ordinary skill in the art, other cuff shapesare contemplated and can be configured without undue experimentationprovided with the present disclosure. In one embodiment cuff 704 can besubstantially cylindrical in shape. In another embodiment, cuff 704 canbe tapered from its distal end to its proximal end. Its proximal edge708 also can be rounded or beveled, for ease of threading the cable endinto a channel or orifice, for example. In another embodiment, asubstantially flat distal cuff end 710 in provided, maximizing contactbetween cuff end 710 and the cable body 701 at interface 714. In anotherembodiment, the transitional edge 712 between cuff end 710 and cuff side716 can include a bevel or chamfer or can be otherwise sloped. As willbe appreciated by those having ordinary skill in the art, the choice ofmaterials, length of stem 702, and dimensions and shape of cuff 704 canbe varied as desired for different cable uses.

VI. Method of Operation

One method of performing a pipe busting operation now will be described.The method can include attaching a bursting head to a replacement pipeto be installed. For example, this can include assembling a burstinghead of a desired diameter as described above and attaching by standardmeans a replacement pipe to a clevis 632 extending from the burstinghead's distal end. One cable free end, which can include an end seal 720as described above, can be attached to the bursting head. For example,bursting head integrated movement initiator handle 630 is rotated tomove integrated clamping jaw 600 rearward and gripper sections 610 backand away from the interior axial channel. Sealed free cable end 720 isinserted into bursting head axial opening 648 and gripper axial opening614 until it reaches the bursting head interior cable backstop.Integrated movement initiator handle 630 then is rotated in the oppositedirection to move integrated clamping jaw 600 forward such that grippersections move forward into the bursting head tapered cavity 652 and downonto the cable surface. The cable is now engaged with the bursting head.

The other free end of a cable 104, which also can include an end seal720, can be inserted through an underground pipe to be replaced and exitthe pipe through a wall of an exit pit where a cable pulling apparatusis provided. For example, chassis 110, assembled as described above, canbe provided with a laterally positioned piston assembly 111, for exampleclosed path dual piston assembly 200. Dual assembly forward manifold 160protrusions 306 can be inserted into chassis slots 146 and the pistonbody can rest on chassis track 147. Chassis pins 153 can be insertedthrough

manifold protrusion pin holes 307 and into rear chassis pinholes 152.The free cable end can be provided to chassis 110 through faceplateopening 142 in faceplate 140 which abuts the exit pipe wall such thatfaceplate opening 142 aligns with the exit pipe opening.

Front manifold lever 310 can be moved into the unlocked position sopiston assembly 200 can receive the cable end. Moving lever 310 into theunlocked position moves threaded piston 308 rearward into threadedinsert 314 and pushes holding gripper 214 rearward and away from itstapered cavity confinement, compressing spring 218 in the process.Repelling magnets 223 keep gripper member pieces 216 back and away fromthe axial channel.

Rear pulling grippers can be placed in a cable receiving position bypulling trigger lever 444 rearward and moving latch 458 into position onlever pin 462 to hold lever 444 in an open position. This action canallow holding gripper 414 to move rearward along channels 410 providinga space for cable to pass through.

The free cable end can be inserted into the piston assembly throughfront manifold axial opening 304, through interior piston channel 206and exit the piston assembly through rear gripper housing axial opening480. The cable can be held in position for pulling by releasing latch458 and returning it to its resting position in slot 472, and movinglever 310 on front manifold assembly 160 into the locked position.Moving lever 310 into the locked position moves threaded piston forward,decompressing spring 218 and pushing gripper214 forward into the housingtapered cavity and onto the cable surface. The cable pulling apparatusnow is ready for operation.

The pistons then can be actuated back and forth using standard hydrauliccontrols and pull cable through the assembly as described above. Oncethe bursting head reaches the faceplate, front manifold lever 310 canagain be moved into the unlocked position, and rear assembly latch 458engaged with trigger arm pin 462 to disengage cable. Chassis pins 153can be extracted from their pin holes and piston assembly 200 can bemoved forward so manifold pin holes 307 align with font chassis pinholes150, and pins 153 reinserted. Font manifold lever 310 can again bemoved into a locked position and rear assembly latch released from pin462 and returned to its resting position. Pistons can again be actuatedto pull the bursting head into the chassis interior. Bursting headintegrated handle 630 then can be rotated to move integrated clampingjaw 600 distally relative to the bursting head tapered cone andreleasing the cable end inside. Front manifold lever 310 once again canbe moved into the unlocked position and latch 458 engaged with pin 462.The cable now can be extracted forward from the bursting head, throughpiston assembly channel 206 and out front manifold axial opening 304.The bursting head can be released from the an attached replacement pipeby removing clevis pin 634 from clevis 632.

In the example where a pipe extraction chassis is used, cable attachmentto a bursting head and piston assembly can be the same as describedabove. In this method, a pipe extraction chassis can be provided to anexit pit. Dual piston assembly 200 for example can be provided to thechassis by inserting chassis dowels 524 into piston assembly dowelopenings 523 on the assembly's front manifold protrusions. Pipeextraction chassis faceplate can abut the exit pipe pit wall withfaceplate opening 508 aligning with the exposed pipe end. Pipe splitter534 can be provided to chassis backplate 509 such that pipe splitteraxial opening 537 aligns with backplate opening 513. One free end of acable can be attached to a bursting head as described above. The otherend can be threaded through the underground pipe to be replaced andpassed through faceplate opening 508, through pipe splitter axialopening and backplate opening 513. Cable then can be pulled over pulley526 and inserted into the piston front manifold axial opening 304 andpassed through the assembly as described above. The piston actuatedcable pulling operation can proceed as described above. As pipe getsextruded from the exit pipe opening, pipe splitter nose 536 can engagethe pipe and guide it back to be split by blades 535. Split cable piecescan fall away from the chassis backplate 509 and into the exit pit forlater collection.

Embodiments of this disclosure may be embodied in other specific formswithout departing from the spirit or essential characteristics thereof.The present embodiments are therefore to be considered in all respectsas illustrative and not restrictive, the scope of the disclosure beingindicated by the appended claims rather than by the foregoingdescription, and all changes that come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.While illustrative embodiments have been illustrated and described, itwill be appreciated that various changes can be made therein withoutdeparting from the spirit and scope of the disclosure.

1.-62. (canceled)
 63. An integrated cable clamping and release mechanismuseful in a bursting head device, the mechanism comprising: (a) agripper component comprising a plurality of gripper members, each memberhaving an inner cable gripping surface, an outer tapered surfacedimensioned to interact with a tapered interior surface of a burstinghead cone, and opposing member adjoining surfaces having an indexedmagnet embedded therein and competent to repel a magnet on an adjoiningsurface; (b) a rigid component removably coupled to the distal end ofsaid gripper component and having an axial cavity dimensioned to receivea cable; and (c) means for actuating longitudinal movement of saidintegrated cable clamping and release mechanism in said bursting head,said actuating means being attached to the distal end of said rigidcomponent and having an operational end on the distal exterior surfaceof said bursting head, such that said actuating means can cause saidgripper component to grip a cable surface by initiating forward movementof said integrated mechanism in said bursting head cone, and saidactuating means can cause said gripper component to release said cableby initiating rearward movement of said integrated mechanism in saidbursting head cone.
 64. The mechanism of claim 63 wherein saidstructural component couples to said gripper component by means of aninterlocking lip and groove mechanism.
 65. The mechanism of claim 64wherein said lip extends perpendicularly from the proximal end of saidrigid component, said lip dimensioned to fit in a groove on the innerdistal perimeter of said gripper component.
 66. The mechanism of claim63 wherein the longitudinal movement of said integrated mechanisminitiated by said integrated actuating means occurs by rotationalmovement of said rigid component along a threaded channel in saidbursting head device and engaged with the outer surface of said rigidcomponent.
 67. The mechanism of claim 63 wherein said integratedactuating means operational end comprises a handle.
 68. The mechanism ofclaim 63 wherein said integrated actuating means operational endcomprises a hex screw.
 69. The mechanism of claim 66 wherein saidthreaded channel occurs in a bursting head device endcap.
 70. A burstinghead device comprising: (a) a cone head having an aperture at itsanterior end dimensioned to receive a cable and a tapered inner cavityfor engaging a tapered cable gripping mechanism; (b) an endcap thatattaches to the posterior end of said bursting head device, and (c) anintegrated cable clamping and release mechanism, the mechanismcomprising a tapered gripper component dimensioned to fit in saidbursting head cone inner tapered cavity and comprising a plurality ofgripper members, each member having an inner cable gripping surface andopposing member adjoining surfaces having an indexed magnet embeddedtherein and competent to repel a magnet on an adjoining surface; (d) arigid component removably coupled to the distal end of said grippercomponent and having an axial cavity dimensioned to receive a cable; and(e) means for actuating longitudinal movement of said integrated cableclamping and release mechanism in said bursting head, said actuatingmeans being attached to the distal end of said rigid component andhaving an operational end on the distal exterior surface of saidbursting head, such that said actuating means can cause said grippercomponent to grip a cable surface by initiating forward movement of saidintegrated mechanism in said bursting head cone, and said actuatingmeans can cause said gripper component to release said cable byinitiating rearward movement of said integrated mechanism in saidbursting head cone.
 71. An integrated cable release manifold for a cablepulling device comprising a spring loaded cable gripping assembly havinga cable gripper component with a tapered proximal end and a compressionspring component at its distal end, the manifold comprising: (a) ahousing having an aperture positioned to receive the proximal end of asaid cable gripper comprising a plurality of gripper members, eachmember having an inner cable gripping surface and an outer taperedsurface dimensioned to interact with a tapered interior surface in saidcable pulling device; (b) means for attaching said manifold housing tosaid cable pulling device, and (c) actuating means for initiatinglongitudinal movement of said spring-loaded cable gripping assemblyrearward in said cable pulling device, said actuating means beingattached to an outer surface of said manifold and competent to contactsaid cable gripper proximal end, said contact initiating rearwardmovement of said gripper away from said tapered interior surface,compression of said distally located spring, and release of said grippermembers from said cable surface.
 72. The manifold of claim 71 whereinsaid gripper members further comprise opposing member adjoining surfaceshaving an indexed magnet embedded therein and competent to repel amagnet on an adjoining surface.
 73. The manifold of claim 71 whereinsaid actuating means comprises a multi-lead threaded piston thatcontacts said proximal gripper end by rotational movement of said pistonalong a threaded channel in said aperture.
 74. The manifold of claim 73wherein rotation of said threaded piston is initiated by a leverattached to an outer surface of said threaded piston.
 75. The manifoldof claim 71 wherein release of said actuating means contact from saidgripper component proximal end initiates decompression of said springand forward longitudinal movement of said gripper members into saidtapered interior and onto said cable surface.
 76. A method formodulating the rearward movement of a cable gripper along a channel, thecable gripper comprising a plurality of gripper sections having an innercable gripping surface and an outer surface comprising a ridge engagedwith said channel and allowing travel of said gripper section along saidchannel, the method comprising the step of: providing an engagementmeans attached to said piston assembly and configured to removablyengage said cable gripper in said channel during piston operation, saidengagement means comprising a torsion spring activated by said gripperrearward movement when said engagement means is engaged with saidgripper and configured to modulate the speed and distance of saidgripper rearward movement in said channel.
 77. The method of claim 76wherein said gripper channel comprises a groove in a tapered cavity atthe open distal end of a piston rod, such that forward movement of saidpiston rod initiates rearward movement of said gripper along saidchannel and off a cable surface, and rearward movement of said pistonrod initiates forward movement of said gripper along said channel andonto said cable surface, and said engagement means is provided to saidopen distal cavity in a housing.
 78. The method of claim 77 furthercomprising a latching means for holding said engagement means in anextended position away from said gripper distal end when said gripper isoff said cable surface.
 79. A mechanism for modulating the rearwardmovement of a cable gripper along a channel in a tapered cavity, thecable gripper comprising a plurality of gripper sections having an innercable gripping surface and an outer surface comprising a ridge engagedwith a said channel and allowing travel of said gripper section alongsaid channel, the mechanism comprising: (a) engagement means forremovably engaging said cable gripper in said channel, said engagementmeans comprising a torsion spring activated by said gripper rearwardmovement when said engagement means is engaged with said gripper andcompetent to modulate the speed and distance of said gripper rearwardmovement in said channel; and (b) an engagement means housing containingsaid engagement means and comprising means for attaching to the distalend of said tapered cavity.
 80. The mechanism of claim 79 furthercomprising a latching means for holding said engagement means in anextended position away from said gripper distal end when said gripper isoff said cable surface, said latching means comprising a hinged barattached to said engagement means housing, said bar defining an angledchannel that engages a pin on an engagement means lever arm and holdssaid arm in an extended position.
 81. An internal anti-rotationmechanism for a single cylinder piston assembly configured to pull cablethrough space, the mechanism comprising: (a) a hollow piston rod havingan axial opening for receiving a cable, the interior surface of saidpiston rod dimensioned to receive a shaft and allow longitudinalmovement of said piston rod along a portion of said shaft's outersurface, said piston rod interior surface further comprising a slotalong its longitudinal axis; and (b) a hollow shaft dimensioned to fitin said hollow piston rod and having an axial opening for receiving asaid cable, and comprising a protrusion extending perpendicularly fromsaid shaft outer surface and dimensioned to fit in said slot, such thatlateral rotation of said piston rod relative to said shaft is inhibitedas said piston rod travels longitudinally along said shaft.
 82. Themechanism of claim 81 wherein said piston rod comprises a plurality ofslots disposed about its interior surface and said shaft comprises amatching plurality of protrusions disposed about its exterior surface.83. The mechanism of claim 81 wherein said protrusion is provided at anaxial opening of said shaft in said rod.
 84. The mechanism of claim 83wherein said protrusion is provided by an annulus attached at said axialopening of said shaft.
 85. An internal cable debris containmentmechanism for a single cylinder piston assembly configured to pull cablethrough space, said piston assembly comprising a hollow piston roddimensioned to receive a hollow shaft having a proximal axial openingfor receiving a cable being pulled therethrough, the mechanismcomprising: a telescoping hollow channel dimensioned to allow cablepassage therethrough to the interior of said piston rod, such that thedistal end of said shaft is coupled to the distal end of said pistonrod, and cable debris in said shaft interior is prevented from enteringsaid piston rod interior.
 86. A single cylinder piston assemblyconfigured for pulling a cable through space and comprising the internaldebris containment mechanism of claim
 85. 87. A single cylinder pistonassembly configured for pulling a cable through space and comprising theanti-rotation mechanism, the mechanism comprising: (a) a hollow pistonrod having an axial opening for receiving a cable, the interior surfaceof said piston rod dimensioned to receive a shaft and allow longitudinalmovement of said piston rod along a portion of said shaft's outersurface, said piston rod interior surface further comprising a slotalong its longitudinal axis; and (b) a hollow shaft dimensioned to fitin said hollow piston rod and having an axial opening for receiving asaid cable, and comprising a protrusion extending perpendicularly fromsaid shaft outer surface and dimensioned to fit in said slot, such thatlateral rotation of said piston rod relative to said shaft is inhibitedas said piston rod travels longitudinally along said shaft.
 88. Thesingle cylinder piston assembly of claim 87 further comprising a barrelhousing enclosing said piston rod.
 89. The single cylinder pistonassembly of claim 88 wherein said shaft is attached to said housing andsaid anti-rotation mechanism inhibits lateral rotation of said pistonrod relative to said housing as said piston rod travels longitudinallyalong said shaft.
 90. The single cylinder piston assembly of claim 87further comprising a cable debris containment mechanism, the mechanismcomprising: a telescoping hollow channel dimensioned to allow cablepassage therethrough to the interior of said piston rod, such that thedistal end of said shaft is coupled to the distal end of said pistonrod, and cable debris in said shaft interior is prevented from enteringsaid piston rod interior.
 91. A closed pathway dual cylinder pistonassembly for pulling cable through space, the assembly comprising ahousing, two piston rods, a cable holding gripping assembly and a cablepulling gripping assembly, wherein: (a) said piston rods are dimensionedto fit into two laterally disposed cylindrical cavities in said pistonassembly housing, said cavities having axial openings at the distal endof said housing; (b) said housing further comprises a central axialchannel positioned between said cavities and dimensioned to receive acable, (c) a cable holding gripper assembly is positioned at theproximal end of said cable channel and configured to grip a cablesurface during a piston recovery stroke; and (d) a cable pulling grippermanifold is attached to the free axial distal ends of said piston rodsand comprises a cable pulling gripping assembly configured to grip acable surface during a piston pulling stroke, said pulling gripperassembly aligned with the central axial channel of said housing andhaving an axial opening for receiving a cable.
 92. A piston assembly ofclaim 91 wherein said housing is configured for lateral positioning in achassis.
 93. A piston assembly of claim 91 comprising a spring-loadedholding gripper assembly at its proximal end, said piston assemblyfurther comprising a cable release manifold attached to the proximal endof said assembly and extending forward therefrom, the manifoldconfigured to release said gripper from said cable by compressing saidspring.
 94. The piston assembly of claim 93 wherein said cable releasemanifold comprises: (a) a housing having an aperture positioned toreceive the proximal end of a said cable gripper comprising a pluralityof gripper members, each member having an inner cable gripping surfaceand an outer tapered surface dimensioned to interact with a taperedinterior surface in said cable pulling device; (b) means for attachingsaid manifold housing to said cable pulling device, and (c) actuatingmeans for initiating longitudinal movement of said spring-loaded cablegripping assembly rearward in said cable pulling device, said actuatingmeans being attached to an outer surface of said manifold and competentto contact said cable gripper proximal end, said contact initiatingrearward movement of said gripper away from said tapered interiorsurface, compression of said distally located spring, and release ofsaid gripper members from said cable surface.
 95. The piston assembly ofclaim 94 wherein said manifold further comprises protrusions for lateralpositioning in a chassis.
 96. The piston assembly of claim 95 whereinsaid manifold further comprises means for coupling said assembly to saidchassis.
 97. An apparatus for pulling cable through space comprising achassis, a retractable closed pathway piston assembly and manifold, afront holding cable gripping assembly and integrated release mechanism,and a rear manifold, pulling cable gripping assembly and releasemechanism, wherein: (a) said chassis comprises a faceplate defining ahole and two side panels extending back from opposite sides of said faceplate, each of said two side panels comprising a pin hole extending fromthe top of the side panel down into said panel; (b) said piston assemblycomprises a housing enclosing said piston and comprising an axial holeextending therethrough for receiving said cable, said axial hole furthercomprising a spring-loaded holding cable gripping assembly; (c) saidrear manifold attached to said piston and comprising a pulling gripperassembly and integrated pulling gripper release mechanism; (d) saidfront manifold, attached to said housing and extending forwardtherefrom, defines an axial hole for receiving said cable comprising anintegrated actuating means for releasing said spring-loaded holdinggripper assembly through said axial opening, said front manifold furthercomprising opposing protrusions, each said protrusion comprising a pinhole that can be aligned with the pin hole of said corresponding sidepanel such that said piston assembly and attached manifolds can beretracted within said chassis away from said faceplate and held in saidretracted position; and (e) a pin competent to fit in said pinholes andhold said piston assembly and attached manifolds in said retractedposition within said chassis.
 98. The apparatus of claim 97 wherein saidclosed pathway piston assembly comprises the dual cylinder pistonassembly.
 99. The apparatus of claim 98 wherein said dual cylinderpiston assembly comprises a housing, two piston rods, a cable holdinggripping assembly and a cable pulling gripping assembly, wherein: (a)said piston rods are dimensioned to fit into two laterally disposedcylindrical cavities in said piston assembly housing, said cavitieshaving axial openings at the distal end of said housing; (b) saidhousing further comprises a central axial channel positioned betweensaid cavities and dimensioned to receive a cable, (c) a cable holdinggripper assembly is positioned at the proximal end of said cable channeland configured to grip a cable surface during a piston recovery stroke;and (d) a cable pulling gripper manifold is attached to the free axialdistal ends of said piston rods and comprises a cable pulling grippingassembly configured to grip a cable surface during a piston pullingstroke, said pulling gripper assembly aligned with the central axialchannel of said housing and having an axial opening for receiving acable.
 100. The apparatus of claim 97 wherein said closed pathway pistonassembly comprises the single cylinder piston assembly.
 101. Theapparatus of claim 100 wherein said single cylinder piston assemblycomprises an anti-rotation mechanism.
 102. The apparatus of claim 101wherein said anti-rotation mechanism comprises: (a) a hollow piston rodhaving an axial opening for receiving a cable, the interior surface ofsaid piston rod dimensioned to receive a shaft and allow longitudinalmovement of said piston rod along a portion of said shaft's outersurface, said piston rod interior surface further comprising a slotalong its longitudinal axis; and (b) a hollow shaft dimensioned to fitin said hollow piston rod and having an axial opening for receiving asaid cable, and comprising a protrusion extending perpendicularly fromsaid shaft outer surface and dimensioned to fit in said slot, such thatlateral rotation of said piston rod relative to said shaft is inhibitedas said piston rod travels longitudinally along said shaft.
 103. Theapparatus of claim 101 wherein said single cylinder piston assemblyfurther comprises a cable debris containment mechanism, the mechanismcomprising: a telescoping hollow channel dimensioned to allow cablepassage therethrough to the interior of said piston rod, such that thedistal end of said shaft is coupled to the distal end of said pistonrod, and cable debris in said shaft interior is prevented from enteringsaid piston rod interior.
 104. A system for pulling a bursting head andattached cable through an existing pipe underground, the systemcomprising a bursting head device, a cable pulling apparatus,replacement pipe, and a cable, wherein: (a) said bursting head devicecomprises: a cone head having an aperture at its anterior enddimensioned to receive a cable and a tapered inner cavity for engaging atapered cable gripping mechanism; an endcap that attaches to theposterior end of said bursting head device, and an integrated cableclamping and release mechanism, the mechanism comprising a taperedgripper component dimensioned to fit in said bursting head cone innertapered cavity and comprising a plurality of gripper members, eachmember having an inner cable gripping surface and opposing memberadjoining surfaces having an indexed magnet embedded therein andcompetent to repel a magnet on an adjoining surface; a rigid componentremovably coupled to the distal end of said gripper component and havingan axial cavity dimensioned to receive a cable; and means for actuatinglongitudinal movement of said integrated cable clamping and releasemechanism in said bursting head, said actuating means being attached tothe distal end of said rigid component and having an operational end onthe distal exterior surface of said bursting head, such that saidactuating means can cause said gripper component to grip a cable surfaceby initiating forward movement of said integrated mechanism in saidbursting head cone, and said actuating means can cause said grippercomponent to release said cable by initiating rearward movement of saidintegrated mechanism in said bursting head cone; and (b) said pullingapparatus comprises a chassis, a retractable closed pathway pistonassembly and manifold, a front holding cable gripping assembly andintegrated release mechanism, and a rear manifold, pulling cablegripping assembly and release mechanism, wherein: said chassis comprisesa faceplate defining a hole and two side panels extending back fromopposite sides of said face plate, each of said two side panelscomprising a pin hole extending from the top of the side panel down intosaid panel; said piston assembly comprises a housing enclosing saidpiston and comprising an axial hole extending therethrough for receivingsaid cable, said axial hole further comprising a spring-loaded holdingcable gripping assembly; said rear manifold attached to said piston andcomprising a pulling gripper assembly and integrated pulling gripperrelease mechanism; said front manifold, attached to said housing andextending forward therefrom, defines an axial hole for receiving saidcable comprising an integrated actuating means for releasing saidspring-loaded holding gripper assembly through said axial opening, saidfront manifold further comprising opposing protrusions, each saidprotrusion comprising a pin hole that can be aligned with the pin holeof said corresponding side panel such that said piston assembly andattached manifolds can be retracted within said chassis away from saidfaceplate and held in said retracted position; and a pin competent tofit in said pinholes and hold said piston assembly and attachedmanifolds in said retracted position within said chassis.
 105. A methodfor pulling pipe through a tunnel underground, the method comprising:(a) providing a system of claim 103; (b) attaching the front end of saidcable to said bursting head device through the actuating means in saidbursting head device; (c) inserting the rear end of said cable throughsaid face plate hole and the central axial holes of said piston assemblyhousings and manifolds; (d) pulling said bursting head device throughsaid tunnel by means of said cable until said bursting head deviceappears from said tunnel and abuts said faceplate; (e) releasing saidholding gripper assembly from the cable surface by initiating saidactuating means on said front manifold; (f) releasing said pullinggripper assembly from the cable surface by said latching means on saidrear manifold; (g) retracting said piston assembly and attachedmanifolds back along said slots such that the pinholes on the frontmanifold protrusions are now aligned with the corresponding pin holes onsaid chassis side panels; (h) holding said assembly in said retractedposition by placing pins in said aligned pin holes, and (i) pulling saidbursting head device through said faceplate and into said chassis, anddisconnecting said bursting head device from said cable and said pipe.